The Seleucid Empire ( sih-LEW-sid) was a Greek state in West Asia during the Hellenistic period. It was founded by the Macedonian general Seleucus I Nicator in 312 BC, following the division of Alexander the Great's Empire, and was ruled by the Seleucid dynasty from Seleucia and later Antioch until its annexation by the Roman Republic under Pompey in 63 BC.
After receiving the Mesopotamian regions of Babylonia and Assyria in 321 BC, Seleucus I began expanding his dominions to include the Near Eastern territories that include modern Iraq, Iran, Afghanistan, Syria and Lebanon, all of which had been under Macedonian control after the fall of the former Achaemenid Empire. At the Seleucid Empire's height, it had consisted of territory that covered Anatolia, Persia, the Levant, Mesopotamia and what are now modern Kuwait, Afghanistan and parts of Turkmenistan in Central Asia.
The Seleucid Empire was a center of Hellenistic culture. Greek customs and language were privileged; the wide variety of local traditions had been generally tolerated, while an urban Greek elite had formed the dominant political class and was reinforced by steady migration from Greece. The empire's western territories were repeatedly contested with Ptolemaic Egypt—a rival Hellenistic state. To the east, the Seleucid–Mauryan war with the Indian ruler Chandragupta of the Maurya Empire in 305 BC led to a political alliance and the cession of territories conquered by Alexander along the Indus River, east of Bactria.
In the early second century BC, Antiochus III the Great fought the Roman–Seleucid war into Hellenistic Greece, but his attempts were thwarted by the Roman Republic and its Greek allies at the Battle of Magnesia. The Seleucids were forced to pay war reparations and had to relinquish territorial claims west of the Taurus Mountains in southern Anatolia, marking the gradual decline of the empire. Mithridates I of Parthia conquered much of the remaining eastern lands of the Seleucid Empire in the mid-second century BC, including Assyria and what had been Babylonia, while the independent Greco-Bactrian Kingdom continued to flourish in the northeast. The Seleucid kings were thereafter reduced to a rump state in Syria after a civil war, until their conquest by Tigranes the Great of Armenia in 83 BC, and ultimate overthrow by the Roman general Pompey in 63 BC.
Name
Contemporary sources, such as a loyalist decree honoring Antiochus I from Ilium, in Greek language define the Seleucid state both as an empire (ἀρχή, archḗ) and as a kingdom (βασιλεία, basileía). Similarly, Seleucid rulers were described as kings in Babylonia.
The rulers did not describe themselves as being of any particular territory or people, but starting from the 2nd century BC, ancient writers referred to them as the Syrian kings, the kings of Syria or of the Syrians, the kings descended from Seleucus Nicator, the kings of Asia, and other designations.
History
Partition of Alexander's empire
Alexander, who quickly conquered the Persian Empire under its last Achaemenid dynast, Darius III, died young in 323 BC, leaving an expansive empire of partly Hellenised culture without an adult heir. The empire was put under the authority of a regent, Perdiccas, and the vast territories were divided among Alexander's generals, who thereby became satraps at the Partition of Babylon, all in that same year.
Rise of Seleucus
Alexander's generals, known as diadochi, jostled for supremacy over parts of his empire following his death. Ptolemy I Soter, a former general and then current satrap of Egypt, was the first to challenge the new system, which eventually led to the demise of Perdiccas. Ptolemy's revolt created a new subdivision of the empire with the Partition of Triparadisus in 320 BC. Seleucus, who had been "Commander-in-Chief of the Companion cavalry" (hetairoi) and appointed first or court chiliarch (which made him the senior officer in the Royal Army after the regent and commander-in-chief Perdiccas since 323 BC, though he helped to assassinate him later) received Babylonia. Antigonus eventually forced Seleucus out of Babylon around 315 BC and he fled to Egypt.
At the battle of Gaza in 312 BC, Ptolemy I Soter and Seleucus defeated Demetrius. After this battle Seleucus spent the winter in Syria, and with his army travelled across Syria and advanced back toward Babylon, arriving in there in April 311 BC.
Babylonian War and initial conquests (311–309 BC)
Seleucus declared himself "general" and "strategos autokrater of Asia" around May-June 311 BC shortly after arriving in Babylon. His goal was to usurp Antigonos' power. Antigonos reoccupied Syria shortly thereafter. When Seleucus arrived in Babylon he faced resistance from the Antigonid military governor Diphilus, who commanded a citadel in the city. Seleucus and his army captured the citadel and took control of Babylon in August 311 BC, implying months of resistance.
Nicanor, a prominent Antigonid loyalist and military commander, raised a substantial force that aimed to retake Babylon from Seleucus. He and his army marched from Ecbatana (most likely utilizing the Royal Road that passed along the Diyala River valley) and eventually reached Opis near the Tigris around September 331 BC.
Seleucus responded immediately with a far smaller army and hid his men in the marshes along the Tigris. Nicanor was unaware of Seleucus' presence in the area and set up a camp. Nicanor's guards were attacked stealthily during the night and his army quickly surrendered. Nicanor escaped to Ecbatana and Seleucus proceeded to capture Susiana, where he remained for winter quarters.
Seleucus continued his campaigning the following year in the spring/summer of 310 BC, subsequently launching a full-scale invasion of Media and killing and deposing Nicanor. With Nicanor removed from power, Seleucus was easily able to establish control and conquer the Upper Satrapies.
Antigonos sent his son Demetrius to Babylon with a very large army to recover the city around the summer of 310 BC. Seleucus was absent from Babylon during this time and his general Patrocles conducted the defense. Patrocles ordered all civilians to vacate the city and requested aid from Seleucus, who was in Media. When Demetrius arrived he found the city empty and immediately captured the twin citadels. Demetrius left the city around March 309 BC after facing resistance from the second citadel, and left his general Archelaeus in charge. Around August 310 BC Antigonos' army invaded the city, and a large-scale war broke out between Antigonos and Seleucid in Babylon, which continued up to August 309 BC. The fighting is likely encapsulated by Polyaenus:
Seleucus met Antigonus in battle; the issue of the battle was evenly poised. When night approached both armies decided to adjourn until the next day. The troops of Antigonus, taking off their arms, made camp, but Seleucus instructed his soldiers to eat and sleep in their arms while maintaining battle order. Just before dawn Seleucus’ army advanced, ready armed and drawn up in order of battle, and the Antigonid men, caught unarmed and in disarray, soon yielded the victory to their foes
— Polyaenus, Stratagems, 4.9.1
This was the final war between Seleucus and Antigonos over Babylon. All Antigonid forces were removed from Babylon by 308 BC.
Seleucid–Mauryan War (305–303 BC)
Chandragupta Maurya (Sandrokottos) founded the Maurya Empire in 321 BC after the conquest of the Nanda Empire and their capital Pataliputra in Magadha. Chandragupta then redirected his attention to the Indus River region, and by 317 BC, he conquered the remaining Greek satraps left by Alexander. Expecting a confrontation, Seleucus gathered his army and marched to the Indus. It is said that Chandragupta could have fielded a conscript army of 600,000 men and 9,000 war elephants. According to Appian,
He [Seleucus] crossed the Indus and waged war with Sandrocottus [Maurya], king of the Indians, who dwelt on the banks of that stream, until they came to an understanding with each other and contracted a marriage relationship.
While the Greek sources have been interpreted by some as a Mauryan victory, the details of the conflict, and if there was in fact a pitched battle, are unknown, and Jansani warns that "there are very little details about the battle or skirmish they fought, and that none of the ancient authors depicted either Seleucus or Chandragupta as the clear victor of this battle. This lack of information about the encounter and the ensuing treaty means that it is impossible to reconstruct them." Wheatley and Heckel suggest that the degree of friendly Maurya-Seleucid relations established after the war implies that the hostilities were probably "neither prolonged nor grievous".
Chandragupta received, formalized through a treaty, territory west of the Indus, including the Hindu Kush, modern day Afghanistan, and the eastern part of Balochistan province of Pakistan, bordering on the Indus. Archaeologically, concrete indications of Mauryan rule, such as the inscriptions of the Edicts of Ashoka, are known as far as Kandahar in southern Afghanistan.
It is generally thought that Chandragupta married Seleucus's daughter, or a Macedonian princess, a gift from Seleucus to formalize an alliance. In a return gesture, Chandragupta sent 500 war elephants, a military asset which would play a decisive role at the Battle of Ipsus in 301 BC. In addition to this treaty, Seleucus dispatched an ambassador, Megasthenes, to Chandragupta, and later Deimakos to his son Bindusara, at the Mauryan court at Pataliputra (modern Patna in Bihar state). Megasthenes wrote detailed descriptions of India and Chandragupta's reign, which have been partly preserved to us through Diodorus Siculus. Later Ptolemy II Philadelphus, the ruler of Ptolemaic Egypt and contemporary of Ashoka the Great, is also recorded by Pliny the Elder as having sent an ambassador named Dionysius to the Mauryan court.
The Indians occupy [in part] some of the countries situated along the Indus, which formerly belonged to the Persians: Alexander deprived the Ariani of them, and established there settlements of his own. But Seleucus Nicator gave them to Sandrocottus (Chandragupta Maurya) in consequence of a marriage contract, and received in return five hundred elephants.
Other territories ceded before Seleucus' death were Gedrosia in the south-east of the Iranian plateau, and, to the north of this, Arachosia on the west bank of the Indus River.
Westward expansion
Following his and Lysimachus' decisive victory over Antigonus at the Battle of Ipsus in 301 BC, Seleucus took control over eastern Anatolia and northern Syria.
In the latter area, he founded a new capital at Antioch on the Orontes, a city he named after his father. An alternative capital was established at Seleucia on the Tigris, north of Babylon. Seleucus's empire reached its greatest extent following his defeat of his erstwhile ally, Lysimachus, at Corupedion in 281 BC, after which Seleucus expanded his control to encompass western Anatolia. He hoped further to take control of Lysimachus's lands in Europe – primarily Thrace and even Macedonia itself, but was assassinated by Ptolemy Ceraunus on landing in Europe.
His son and successor, Antiochus I Soter, was left with an enormous realm consisting of nearly all of the Asian portions of the Empire, but faced with Antigonus II Gonatas in Macedonia and Ptolemy II Philadelphus in Egypt, he proved unable to pick up where his father had left off in conquering the European portions of Alexander's empire.
Breakup of Central Asian territories
Antiochus I (reigned 281–261 BC) and his son and successor Antiochus II Theos (reigned 261–246 BC) were faced with challenges in the west, including repeated wars with Ptolemy II and a Celtic invasion of Asia Minor—distracting attention from holding the eastern portions of the Empire together. Towards the end of Antiochus II's reign, various provinces simultaneously asserted their independence, such as Bactria and Sogdiana under Diodotus, Cappadocia under Ariarathes III, and Parthia under Andragoras. A few years later, the last was defeated and killed by the invading Parni of Arsaces—the region would then become the core of the Parthian Empire.
Diodotus, the Seleucid governor for the Bactrian territory, asserted independence in around 245 BC, although the exact date is far from certain, to form the Greco-Bactrian Kingdom. This kingdom was characterized by a rich Hellenistic culture and was to continue its domination of Bactria until around 125 BC when it was overrun by the invasion of northern nomads. One of the Greco-Bactrian kings, Demetrius I of Bactria, invaded India around 180 BC to form the Indo-Greek Kingdoms.
The rulers of Persis, called Fratarakas, also seem to have established some level of independence from the Seleucids during the 3rd century BC, especially from the time of Vahbarz. They would later overtly take the title of Kings of Persis, before becoming vassals to the newly formed Parthian Empire.
The Seleucid satrap of Parthia, named Andragoras, first claimed independence, in a parallel to the secession of his Bactrian neighbour. Soon after, however, a Parthian tribal chief called Arsaces invaded the Parthian territory around 238 BC to form the Arsacid dynasty, from which the Parthian Empire originated.
Antiochus II's son Seleucus II Callinicus came to the throne around 246 BC. Seleucus II was soon dramatically defeated in the Third Syrian War against Ptolemy III of Egypt and then had to fight a civil war against his own brother Antiochus Hierax. Taking advantage of this distraction, Bactria and Parthia seceded from the empire. In Asia Minor too, the Seleucid dynasty seemed to be losing control: the Gauls had fully established themselves in Galatia, semi-independent semi-Hellenized kingdoms had sprung up in Bithynia, Pontus, and Cappadocia, and the city of Pergamum in the west was asserting its independence under the Attalid dynasty. The Seleucid economy started to show the first signs of weakness, as Galatians gained independence and Pergamum took control of coastal cities in Anatolia. Consequently, they managed to partially block contact with the West.