We are searching data for your request:
Upon completion, a link will appear to access the found materials.
321 BCE - 315 BCE
Seleucos rules the satrapy of Babylon.
c. 312 BCE - 63 BCE
Emperor Chandragupta signs a treaty with Seleucos I, establishing borders and giving the Punjab to Chandragupta in return for 500 war elephants.
305 BCE - 281 BCE
301 BCE - 299 BCE
281 BCE - 261 BCE
Seleucids successfully defeat the Galatian Celts in the 'Elephant Battle'.
274 BCE - 271 BCE
The first Syrian war, marking the beginning of the contest between the Ptolemies and the Seleucids for Phoenicia and Coele-Syria.
Eumenes rebels and wins against the Seleucid Antiochus I. Beginning of the Pergamon Empire.
261 BCE - 246 BCE
Galatians defeat Seleucus II in a battle near Ancyra.
223 BCE - 187 BCE
Reign of Antiochus III the Great who reunites the Seleucid Empire.
210 BCE - 204 BCE
The Seleucid king, Antiochus III Megas signs a treaty with Philip V of Macedon to divide Egypt and its overseas possessions between them.
c. 195 BCE
Facing the threat of being handed to the Romans after the Second Punic War, Hannibal flees to the Seleucid court of Antiochus III and becomes his advisor.
Battle of Magnesia ad Sipylum, disastrous defeat for Antiochos III against Romans.
c. 188 BCE
The treaty of Apamea Kibotos. Peace and alliance is established between the Seleucid Empire and Rome joined by its allies, such as Pergamon and Rhodes. The Seleucids have to evacuate all the land and the cities from Asia Minor and to pay a huge war indemnity.
175 BCE - 163 BCE
Persis passes from Seleucid to Parthian domination.
140 BCE - 138 BCE
Cilician Pirates grow in power under the reign of Diodotus Tryphon of the Seleucid Empire.
65 BCE - 63 BCE
Seleucid Empire: one of the successor states after the death of Alexander the Great. Its official name was "Asia".
After the death of Alexander the Great in the afternoon of 11 June 323 BCE, his empire was divided by his generals, the Diadochi. One of them was his friend Seleucus, who became king of the eastern provinces - more or less modern Afghanistan, Iran, Iraq, Syria, and Lebanon, together with parts of Turkey, Armenia, Turkmenistan, Uzbekistan, and Tajikistan. His kingdom was to have two capitals, which were founded in c.300: Antioch in Syria and Seleucia in Mesopotamia. Babylon and Seleucia in Pieria were other important cities.
The empire was, like the empire of Alexander, the continuation of the empires before: the Assyrian, Babylonian, and the Achaemenid Empire. This continuity is not in doubt, but scholars disagree about the question whether the Seleucids deliberately presented themselves as successors of the Achaemenids and intended to use the old structures.
Seleucus' reign lasted from 312 to 281 (more. ), and he was succeeded by his descendants, who continued to govern this assembly of countries for more than two centuries. However, in the mid-240s, during a brief interregnum, the Seleucids started to lose territory in the east, where the Parni nomads settled themselves in the satrapy of Parthia in northeastern Iran. At the same time, the satrapy of Bactria (northern Afghanistan) became independent. Later, the Seleucid king Antiochus III the Great was able to reconquer these territories, during a series of eastern wars between 209 and 204. In the southwest, the Seleucid kings fought several "Syrian wars" with the Egyptians in 200, their king was forced to cede Coele Syria to Antiochus III. Seleucid power had reached its zenith. Yet, Antiochus was also forced to witness the beginning of its demise.
In 196, he crossed the Hellespont in order to add Thrace to his empire (which happened in 194). Seleucid influence in Europe, however, was something that the Romans could not allow to happen, and the inevitable war between the two superpowers broke out in 192. Antiochus received support from many Greek towns and help from the famous Carthaginian general Hannibal, but was defeated and forced to pay a tremendous sum of money. Moreover, the Seleucid empire lost its possessions in what is now Turkey.
The tide was now turning against the Seleucid monarchy. In the west, Rome became too powerful to resist. Worse, they backed the Jews, who liberated themselves in the years after 165 (the Maccabaean revolt). At the same time, the Parni founded the Parthian empire, which snatched away the eastern provinces. The towns in Babylonia, a.o. Seleucia and Babylon, were captured between April and June 141. New losses followed, civil wars between two rival factions of the Seleucid family were inevitable, and in the second quarter of the first century, the Roman generals Lucullus and Pompey the Great made an end to the Seleucid kingdom. The last king was dethroned in 64.
The official name of the kingdom was Asia, but the Romans called it Syria.
Context and Point of Divergence
Context: In the year 168 BCE, the Macedonian phalanx was utterly crushed by the Roman legions at Pydna. This was because as the Roman line withdrew, the phalanx pursued them on to rougher terrain, which created gaps in the phalanx. The Romans exploited this and won, ending the kingdom of Macedon.
PoD: In this timeline, Antiochus IV Epiphanes dies later than in OTL. He also reforms the Seleucid military along Roman lines, seeing the vulnerability of the phalanx.
Key Facts & Information
- The Seleucid Empire was a Hellenistic kingdom from 312 BC to 63 BC.
- It was ruled by the Seleucid dynasty and founded by Seleucus I Nicator after Alexander the Great created division in the empire. Seleucus married his daughter, Helena, to Chandragupta Maurya of the Mauryan Empire when she was just 16 years old.
- Chandragupta sent 500 war elephants in a return gesture, a military decision that would play a decisive role in the Battle of Ipsus in 301 BC.
- Seleucus took control of Babylonia, and from there, he extended its dominions to include most of the near-eastern territories of Alexander.
- This included central Anatolia, Persia, the Levant, Mesopotamia, and what is now Kuwait, Afghanistan, Pakistan, Turkmenistan, and northwestern parts of India.
- The Seleucid Empire consisted of nothing more than Antioch and some Syrian cities by 100 BC. Given the apparent collapse of power and the fall of the empire around them, nobles continued to regularly play kingmakers with occasional interference from Ptolemaic Egypt and other external forces.
FOUNDATION AND EXPANSION
- Alexander the Great defeated the Persian Achaemenid Empire by 330 BC. After his death, his generals were left with a wide empire that encompassed Greece, Mesopotamia, Anatolia, Egypt, the Levant, and Central Asia.
- After a power struggle, they split it between themselves, with Cassander taking Athens, Ptolemy I Soter Egypt, Lysimachus Thrace and Anatolia, Antigonus – who had held Anatolia – dying in 301 BC in the Battle of Ipsus, and Seleucus, claiming Babylon as his own and taking Mesopotamia and Central Asia.
- Alexander had expanded his scope to India, founding cities and leaving them to administer satraps (governors). In 305 BC, King Chandragupta Maurya took back a number of these regions, and Seleucus launched the Seleucid-Mauryan War (305-303 BC), which resulted in a treaty in which Seleucus, in return for trade agreements and protection for its borders, surrendered the regions concerned.
- To rule the eastern regions, he established a capital, the city of Antioch on the Orontes River, which would govern the western part of his empire. He also established the city of Seleucia on the Tigris River.
- Seleucus ruled from Antioch and was co-ruler of Seleucia with his son, Antiochus I Soter (co-ruler 291-281 BC, ruler 281-261 BC.
DEVELOPMENT AND GOVERNMENT
- Antiochus I Soter became emperor and continued the policies of his father to promote a homogeneous empire that combined Hellenistic cultural values with those of the Near East. Scholar Cormac O’Brien explains the policy on Seleucid:
“To rule as Greeks in an immense sea of non-Greeks would have been foolish, if not impossible, and so the Seleucids became both. With their own administration forming merely the newest of a series of ethnic layers that went back centuries, Seleucus and his successors were happy to embrace the cults, gods, and practices of the venerable states that came before them. That was the spirit of Hellenism – the amalgamation of West and East that forged a dynamic new era. And the Seleucid enterprise was its clearest manifestation.”
- The Achaemenid Persian Empire had functioned as well as it did through a policy of centralized government with decentralized administration. The king (emperor) was the supreme power, but he took counsel from his advisors, who passed his decrees to secretaries, who then relayed these to regional governors (the satraps).
- Each satrapy was governed by a governor who had jurisdiction over administrative-bureaucratic matters only, while another official – a trusted general – supervised military/police affairs. This division of responsibilities in every satrapy reduced a regional governor’s chance to amass enough power from a loyal army to attempt a coup. A region’s governor lacked military force, and the general lacked funds to bribe an army to support a takeover of force.
ANTIOCHUS III THE GREAT
- After Seleucus’ death, the Seleucid Empire began declining, but another power was rapidly growing. While the Seleucids were masters of land battle and commerce, the seas (economically and militarily) were ruled by the North African city of Carthage.
- Carthage came into conflict with the small city-state of Rome in 264 BC over a dispute between two Sicilian kingdoms in which each had a vested interest.
- This rivalry culminated in the First Punic War (264-241 BC), which concluded with Rome as the new superpower, and in defeat, Carthage was responsible to pay a large war fee.
- Nevertheless, whatever happened to Rome and Carthage was of little interest to the rulers of Seleucid, as it was opposed to their efforts to hold the empire intact.
- With all the protections against rebellion in place and lenient policies about the cultural and religious traditions of the peoples, the Seleucids also could not contain the appetite of the people for independence to decide their own destiny.
- The fall of the Seleucid Empire was halted and then reversed by the son of Seleucus II Callinicus, Antiochus III (ruler 223-187 BC, known as The Great). He personally led troops across the empire, defeating upstart states and restoring them to the fold.
- Antiochus III campaigned from the Levant to India for six years (c. 210-204 BC), subduing Bactria, making peace with Parthia, and winning out of Egypt, Judea, and Syria.
Seleucid Empire Worksheets
This is a fantastic bundle which includes everything you need to know about the Seleucid Empire across 22 in-depth pages. These are ready-to-use Seleucid Empire worksheets that are perfect for teaching students about the Seleucid Empire which was a Hellenistic state ruled by the Seleucid dynasty, which lasted from 312 BC to 63 BC. It was established by Seleucus I Nicator after the division of the Macedonian Empire, which Alexander the Great had greatly expanded.
Complete List Of Included Worksheets
- Seleucid Empire Facts
- Antiochus III
- Fact or Fiction
- The Kingdoms
- Draw a Line
- Dynasty Wordscape
- Questions Addressed
- The Importance
- Empire Fall
Link/cite this page
If you reference any of the content on this page on your own website, please use the code below to cite this page as the original source.
Use With Any Curriculum
These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.
BC or Before Common Era Timeline
c. 520 BC – Persian armies under Darius I conquer much of Central Asia (inc. Ferghana, Sogdiana, and Chorasmia).
Central Asia – Alexander the Great conquers Bactria, Margiana, Sogdiana, and Ferghana in a multi-year campaign.
Afghanistan – The Seleucids and Mauryans sign a treaty, which gives control over Arachosia & Gedrosia (most of modern Afghanistan & Pakistan) to the Mauryans.
Central Asia – The Satraps of Bactria & Parthia break away from the Seleucid Empire and form their own kingdoms.
Parthia – A Saka tribe called the Parni invade Parthia, killing Andragoras. The Parni adopt the name of their new land and crown their leader as King Arsaces I.
Bactria – King Diodotus II is overthrown by Euthydemus I, beginning the “Euthydemid dynasty”.
Parthia – Seleucid king Antiochus III forces King Arsaces to recognize Seleucid authority.
Bactria – Seleucid king Antiochus III defeats King Euthydemus but is unable to take the capital city (Bactra). Peace is concluded when Euthydemus accepts Seleucid authority.
Mongolia – Xiongnu tribes are united by Maotun to form the Xiongnu Khanate.
India – The Mauryan dynasty is overthrown by the Sunga dynasty when a minister named Pushyamitra Sunga assassinates the last Mauryan emperor.
Afghanistan – Greco-Bactrian king Demetrius I invades Sunga lands in retaliation for the overthrow of the Mauryans. Demetrius seizes Arachosia, Gedrosia, Sindh, and the Punjab region.
Mongolia – The Xiongnu destroy the Tocharian (Yuezhi) federation in Kansu, and some Tochari flee westward towards Wusun and Dzungaria.
Dzungaria – Northern Saka (Sai Wang) tribes are conquered by the Tochari. Some of the Sakas escape and flee south to settle in Ki-pin (near Kashmir).
Iran – Mithradates I becomes King of Parthia after the death of Phraates I.
Bactria – Civil war splits Greco-Bactria when King Antimachus is overthrown by a general named Eucratides. The Euthydemids retreat to India and become known as the “Indo-Greeks”.
Iran – Parthian forces seize Merv & Herat from the Eucratidians during the Greco-Bactrian civil war.
Afghanistan – Menander becomes king of the (Euthydemid) Indo-Greeks.
Dzungaria – The Tochari are defeated by the Wusun (Issedones) and forced to flee to the southeast through Ferghana (Dayuan).
Transoxiana – The Tochari defeat the Western Saka tribes (probably descents of the Massagetae). The Western Sakas flee to the south and west, invading Parthia and Greco-Bactria.
Bactria – Western Sakas defeat King Eucratides II of Greco-Bactria and destroy the city of Alexandria-on-the-Oxus (modern Ai-Khanoum).
Bactria – The Tochari defeat King Heliocles I and destroy the last Greek kingdom in Bactria. The Eucratidians flee and set up a new kingdom in Kabul.
Iran – Saka mercenaries rebel & destroy a Parthian army, killing King Phraates II. His uncle is crowned as Artabanus II.
Central Asia – Chinese envoy Zhang Qian travels to Tochari lands in Bactria, leaving written records of the lands immediately after the Tochari conquest.
Iran – Parthian king Artabanus II is killed fighting a new wave of Saka tribes. He is succeeded by Mithradates II.
Central Asia – A Chinese army under Ban Chao reaches the Black Sea, marking the westernmost expansion of Han authority.
Afghanistan – Parthian forces defeat the Eucratidians and seize control over Arachosia (renamed Sakastan). A Partho-Sakan clan called Suren becomes prominent in the region.
Mongolia – Dingling and Wuhuan tribes rebel against the Xiongnu.
Afghanistan – Indo-Parthian forces seize Gandhara from the Indo-Greeks.
India – Azes I becomes King of the Saka.
Mongolia – Xiongnu Empire breaks into Eastern & Western Khanates.
Dzungaria – Northern Xiongu Khan Zizhou is killed by Han armies, ending the Western Xiongnu Khanate.
Mongolia – The Eastern Xiongnu rebuild their empire in Mongolia.
Antiochus II of Seleucid Empire
King Antiochus II of the Seleucid Dynasty was the third ruler of this particular line of kings. He was born to King Antiochus I Soter in 286 B.C. which is where he appears on the Bible Timeline Poster with World History. He was named King Antiochus II Theos or “god” during the second Syrian war that erupted during his reign. During the struggle with Egypt, he encountered a tyrant named Timarchus who was harassing a group of people known as the Milesians.
While King Antiochus II Theos was in power he had to deal with a number of problems within his empire. Most of these problems were created from the minor kings and governors who continued to rebel and keep intrigue within their courts. Some governors managed to pull away from his empire such as Andragoras who ruled over Parthia. Another governor named Diodotus led another one of his provinces named Bactria into revolt. While these events were occurring King Antiochus II Theos was engaged in a war with the Egyptian Ptolemies over the land of Syria. He eventually made peace with the ruling Ptolemy and turned his attention back to the rebellions. When he did it was too late because Parthia had become an independent kingdom that cut off India from his empire.
King Antiochus II didn’t spend a lot of time trying to regain lost territory. He knew that his forces couldn’t contain every last area of the empire. He ensured that the areas that were situated in Asia Minor and Syria were under his control. King Antiochus II already realized that it would have been a waste of time and manpower to try and contain all of the growing unrest throughout every last part of his empire.These Articles are Written by the Publishers of The Amazing Bible Timeline
Quickly See 6000 Years of Bible and World History Together
Unique Circular Format – see more in less space.
Learn facts that you can’t learn just from reading the bible
Attractive design ideal for your home, office, church …
While he was losing parts of his empire he had to marry the daughter of Ptolemy II Philadelphus as an act of good faith for the treaty. This marriage proved to be problematic for the king since he was already married to Laodice I. So he divorced her and banished her to Asia Minor. The rejected Queen did everything that she could in order to regain her position. King Antiochus II couldn’t do anything about this situation until Ptolemy II Philadelphus had died. Once Ptolemy died King Antiochus II divorced his daughter Berenice and went back to Laodice I who ended up poisoning the king. She also killed Berenice and their son. She then placed her son Seleucus II on the throne.
The Seleucid Empire began to go into decline under King Antiochus II Theos. He wasn’t able to keep effective rule over the area and this wasn’t totally his fault. Many of the people that were conquered by the Greeks wanted to be free from these rulers. They were sick and tired of the constant warfare that was occurring between the Greek monarchs. The Greeks allowed the conquered lands to live as they have always done in the past, but most of these people wanted to be free from Greek authority. They had been rebelling long before King Antiochus II Theo took over the throne and their rebellion would become a lot more apparent in the immediate years following his reign.
Seleucids and Their Dynasty
The Seleucids were the rulers of the eastern part of Alexander the Great's empire from June 312 to 64 B.C. They were Hellenistic Greek kings in Asia.
When Alexander the Great died, his empire was carved up. His first generation successors were known as the "diadochi". [See map of the Kingdoms of the Diadochi.] Ptolemy took the Egyptian part, Antigonus took the area in Europe, including Macedonia, and Seleucus took the eastern part, Asia, which he ruled until 281.
The Seleucids were the members of the dynasty that ruled Phoenicia, Asia Minor, northern Syria and Mesopotamia. Jona Lendering names the modern states that comprise this area as:
- parts of Turkey, Armenia, Turkmenistan, Uzbekistan, and Tajikistan.
The followers of the eponymous Seleucus I were known as the Seleucids or the Seleucid Dynasty. Their actual names included Seleucus, Antiochus, Diodotus, Demetrius, Philip, Cleopatra, Tigranes, and Alexander.
2,000 BCE Approx. The Story of Abraham – Hebrew Bible
The history of the Middle East is much influenced by the Hebrew Bible. This is a collection of stories that metaphorically illustrate the beliefs and religion of the Jewish people. It is not a literal history.
The Bible describes the emergence of the Israelites as:
Sometime in the 2nd millennium BCE a man called Abraham was living in the city of Ur of the Chaldees (thought to be Tall al-Muqayyar) 300km southeast of Baghdad in lower Mesopotamia. God promised him, his son Isaac, and grandson Jacob that they could have the land of Canaan for themselves and their descendants – the “Promised Land”. Abraham travelled and wandered in the deserts until settling in the land of the Philistines. He died aged 175! His wife Sarah was over 90 when she gave birth to Isaac. Isaac’s son Jacob changed his name to Israel, the father of the Israelites, and his twelve sons founded the twelve tribes of Israel. The Children of Israel were named in the Book of Deuteronomy as God’s “Chosen People”.
Scholars now suggest that the Abraham myth was composed centuries later in late 600 BCE by landowners who had stayed in Judah during the Babylonian captivity and attempted to trace their rights to the land through their father Abraham. The captives returning from Babylon based their claim to the land on another myth – the Moses Exodus story. There was considerable tension between the ones who had stayed and the exiles who had developed exclusivism whilst in Babylon. [See later * – when Cyrus returned the captives].
The Seleucid Empire was a Hellenistic (or Ancient Greek) successor state of Alexander the Great's empire. At its greatest extent, the Empire covered central Anatolia, the Levant, Mesopotamia, Persia, Turkmenistan, Pamir and the Indus Valley.
Primarily, it was the successor to the Achaemenid Empire of Persia, and was followed there by the Islamic Caliphate (Rashidun Empire) conquest and rule, from 650s to 660s AD. Later on, much of this area became part of the Umayyad Empire and then the Abbasid Empire.
There were over 30 kings of the Seleucid dynasty from 323 to 63 BC.
Alexander the Great had conquered the Persian Empire but later died young, leaving his huge empire of partly Hellenized culture without an adult heir.
The empire was put under the management of a regent named Perdiccas in 323 BC, and the territories were divided between Alexander's generals, who thereby became satraps, at the Partition of Babylon. Leaders who thought they should have more, started wars to get it. Soon the various parts of the empire were fighting each other.
Seleucus I Soter was one of Alexander's generals who received a portion of the huge empire Alexander had carved out. He received huge expanses of land in Syria, Babylon, Anatolia, even as far out as India. When Perdiccas was killed in a political assassination by Ptolemy of Egypt, the empire that was barely held together then splintered apart. The Seleucid Empire quickly expanded, eventually taking parts of Thrace in the west and advancing past the Indus in the East.
Seleucus I clashed several times with his southern rival for power, the Ptolemaic Dynasty. The Ptolemaic Dynasty controlled most of Egypt and the lands around it, and would fight the Seleucid Empire on many occasions for control of Syria. Seleucus I conquered much of Anatolia, and was preparing to invade Macedonia, when he was assassinated. This momentarily put an end to the Seleucid Empire's ambitions in Greece. After Seleucus I died, his heirs spent much of their time and money trying to maintain the enormous empire they had inherited. In this, they were rather successful, but the vastness of the empire defied attempts by the successors of Seleucus to control it effectively.
Alexander the Great’s death in 323 BC meant the end of the Macedonian Empire he had conquered, which disintegrated into competing Hellenistic Kingdoms with the same speed as it had been created. Perhaps the most successful of the Warlords that fought for dominance was Seleucus (c. 358 BC — 281 BC), who managed to secure for himself most of Macedonian Asia. The Seleucid Empire was formally established with the recovery of Babylon from Seleucus’ rival, Antigonos, in October 312. Seleucus had been married to Apame, daughter of the Sogdian satrap Spitameneses, since 324, on Alexander’s orders. Unlike other Macedonian generals, he did not divorce his wife after Alexander’s death, either because she was politically useful for him in controlling the natives of his eastern provinces or because he truly loved her (possibly both). Seleucus invaded Punjab in India in 305, confronting unsuccessfully Chandragupta Maurya (Sandrokottos), founder of the Maurya Empire. He was forced to cede vast territories west of the Indus in exchange for elephants which he used to defeat Antigonus in the battle of Ipsos in 301.
Seleucus then made an important decision when he moved the capital, and thus the center of political power, away from Iran and in Syria. In 300, he founded Antioch on the lower Orontes in north Syria and constructed two artificial harbors, Seleucia and Laodicea. More than 1,700 miles separated his capital from his outposts in Jaxartes and this made control of the eastern provinces a difficult task and later on allowed them to declare independence, leading to the creation of the Greco-Bactrian Kingdom and the Indo-Greek Kingdoms. However, his move of the capital in Syria had advantages. He could closely monitor the Mediterranean and Greece, from which he could import ideas and, most importantly, men. He could also check Ptolemaic Egypt’s advance in Palestine, where a series of Egyptian-Seleucid wars were fought.
By the time of his death, in 281, his empire stretched from Bactria to Minor Asia and he had even established a foothold in Thrace. It is very likely that he had ambitions on the Macedonian throne itself and, had he not been assassinated, he might have been able to restore unity to the Macedonian Empire. Alas, he was assassinated by Ptolemy Ceraunus, thus putting an end to the Seleucid ambitions of uniting the Empire. From now on, Alexander’s Empire was dead, never to be reunited, and a new one was born: the Seleucid Empire.
Seleucus was succeeded by Antiochus I (reigned 281–261 BC). An interesting incident about him has to do with his love for Stratonice, the daughter of Antipater. She was married to Seleucus but, after discovering that his son was lovesick with her, he gave up Stratonice in marriage to the young prince in 294. When Antiochus came to the throne, the situation was not ideal for the new ruler his control of parts of the Empire, especially in the east, was tenuous at best. Nomads from the “vast plain stretching out interminably” in Central Asia raided the eastern provinces and in 280 they managed to get as far as Tirmidh and Herat. Meanwhile, Seleucid territories in Western Asia Minor were being contested. But Antiochus was not to be underestimated and was no less capable than his father.
He expelled the nomads, restored ravaged cities, rebuild the citadel of Marv and constructed a rampant of beaten earth and brick (20 meters high and 270 km long) in Marv oasis. In 275 he defeated the Gauls, who raided Minor Asia, with the use of elephants. But his conflict with Egypt over Palestine was to be the cause of much trouble for the Empire, as it depleted resources which could be used to defend and maintain control of the east. Antiochus had to ask his Bactrian province to send him 20 elephants in order to use them against Egypt, thus leaving the province undefended in the face of renewed nomad raiding. Antiochus’ hold in Asia Minor was no more secure. The cities there, although professing loyalty to the King, regarded themselves as being outside of the Empire and their allegiance had to be reaffirmed when a new King came to the throne.
All those problems exacerbated during the reign of Antiochus’ successor: Antiochus II (reigned 261–246 BC), when he died, left the Empire far weaker than when he had taken the throne. General Diodotus in Bactria declared his independence from his Seleucid overlords and had formed the Greco-Bactrian Kingdom which was to defend Bactria for almost 130 years against nomads and conquered many peoples in India, leading to the creation of the Indo-Greek Kingdom. When Andragoras, Satrap of Parthia, too revolted against his lord, his province was overrun by the Parni led by Arsaces. Those nomads were to establish the Parthian Empire which would later on dominate Iran and clash repeatedly with the Roman Empire. But, for now, the Parthians were contained due to the cooperation between Seleucids and Bactrians to keep them in check.
The death of Antiochus II in 246 led to a dynastic war, one of the many that ravaged and eventually brought down the Seleucid Empire. Laodice, divorced wife of Antiochus, and Berenice, widow and sister to Ptolemy III of Egypt, fought out. Seleucus II Callinicus (reigned 246 — 225 BC), son of Antiochus II and Laocide, was thus defeated by Ptolemy and later had to fight a civil war against his brother Antiochus Hierax. He lost direct control of much of Asia Minor, but he managed to retain the allegiance of Miletos and Smyrna.
Although the Seleucid Empire was weakened, it was still not dead and Antiochus III (reigned 222–3 July 187 BC) would prove that a capable King could restore the Empire to its former glory. Antiochus III alone managed to restore Seleucid control, albeit nominal, in Bactria and the Far East and rightfully gained the title of “Great King”. Polybios said of Antiochus’ anabasis of 212–205: “‘It was this campaign which made him appear worthy of royalty, not only to the peoples of Asia but to those in Europe as well”. The rich booty he gained from that campaign allowed him to defeat Egypt and acquire Palestine in 200. This was the high point of the Seleucid Empire. It seemed as it could reign supreme in the Hellenistic East and be restored to great power status. But it was not to be in 189 he lost a war with Rome and was forced to cede Western Minor Asia. His conquests in the east too were reversed by this setback. Yet he maintained control of Western Iran, from Ecbatana to the Persian Gulf.
Renewed dynastic intrigues and infighting among the Seleucids were exploited by the Parthians. The Parthian King Mithridates I (171–139/8 BC) took control of Turiva and Asponius from the Bactrians. He then expanded westwards towards the Seleucid realm, conquered Media and invaded Mesopotamia, taking over the cities of Seleucia and Ctesiphon. In 141, he had taken control of Babylon. Mithridates had turned Parthia from a small kingdom to an imperial contender.
Somewhat surprising is the fact that not only Greeks, but also Iranians remained loyal to the Seleucids and appealed for Seleucid help against the Parthians. King Demetrios II set out for Media, although his decision to campaign east may have more to do with his desire to get rid of his political opponent Tryphon from Syria than with the appeal of the residents of the province. He was popular among the populace but popularity alone does not win a war he was captured in 139. His brother, Antiochus VII was far more successful, as he managed to recover Babylon and Media from the Parthians but was unfortunately killed in a skirmish in 129. Thus Seleucid domination of Iran, and with it its status as a great empire, ended once and for all.
While the Seleucid power was collapsing, the Partian King Mithridates II (124/3–88/7) was consolidating Parthia as an imperial state. He secured Parthian control over northern Mesopotamia. In 97, Mithridates subjugated Armenia. The Euphrates River became the border between Parthia and the expanding power of Rome. In contrast to the expanding power of the Parthians, the Seleucids controlled only Antioch and a few Syrian cities. Yet, despite the precariousness of the situation, the infighting and dynastic intrigues continued to ravage the Seleucids. The Kings and their political opponents squabbled over a realm reduced to nothingness and kept alive only because Rome did not want to assume responsibility for Syria. When Rome finally decided to assume that responsibility, the Seleucid Empire came to an end in 63 BC. Syria became a Roman province.
The Seleucid empire's geographic span, from the Aegean Sea to what is now Afghanistan and Pakistan, created a melting pot of various peoples, such as Greeks, Armenians, Persians, Medes, Assyrians and Jews. The immense size of the empire, followed by its encompassing nature, encouraged the Seleucid rulers to implement a policy of ethnic unity—a policy initiated by Alexander.
The Hellenization of the Seleucid empire was achieved by the establishment of Greek cities throughout the empire. Historically significant towns and cities, such as Antioch, were created or renamed with more appropriate Greek names. The creation of new Greek cities and towns was aided by the fact that the Greek mainland was overpopulated and therefore made the vast Seleucid empire ripe for colonization. Colonization was used to further Greek interest while facilitating the assimilation of many native groups. Socially, this led to the adoption of Greek practices and customs by the educated native classes in order to further themselves in public life, and at the same time the ruling Macedonian class gradually adopted some of the local traditions. By 313 BC, Hellenic ideas had begun their almost 250-year expansion into the Near East, Middle East, and Central Asian cultures. It was the empire's governmental framework to rule by establishing hundreds of cities for trade and occupational purposes. Many of the existing cities began—or were compelled by force—to adopt Hellenized philosophic thought, religious sentiments, and politics although the Selecuid rulers did incorporate Babylonian religious tenets to gain support. 
Synthesizing Hellenic and indigenous cultural, religious, and philosophical ideas met with varying degrees of success—resulting in times of simultaneous peace and rebellion in various parts of the empire. Such was the case with the Jewish population of the Seleucid empire the Jews' refusal to willingly Hellenize their religious beliefs or customs posed a significant problem which eventually led to war. Contrary to the accepting nature of the Ptolemaic empire towards native religions and customs, the Seleucids gradually tried to force Hellenization upon the Jewish people in their territory by outlawing Judaism. This eventually led to the revolt of the Jews under Seleucid control, which would later lead to the Jews achieving independence from the Seleucid empire.