The Seleucid Empire (312–63 b.c.e.) was the largest of the Hellenistic states that emerged from the conquests of Alexander the Great. Seleucus I (c. 358–281 b.c.e.), one of Alexander’s generals, founded the Seleucid Empire in 312. Seleucus, who took the title Nicator, or "victor", was the most successful combatant in the bloody and protracted wars of the Diadochi.
The empire he founded stretched from the Middle East and Asia Minor to Bactria in Central Asia. Seleucus initially claimed the Macedonian conquests in India as well but was forced to abandon them to Chandragupta II around 305 b.c.e. Seleucus was later killed by Ptolemy Keraunos, a member of the ruling Egyptian dynasty.
The Seleucid dynasty drew from both Greco-Macedonian and Near Eastern traditions of rule. The Seleucid monarch was theoretically not identiﬁ ed with a particular people, but in practice, was Greek in culture. Greeks and Macedonians constituted the vast majority of the kingdom’s governing elite, known as the king’s friends.
The Seleucids claimed a particularly strong relationship with the Greek god Apollo but also patronized the traditional religion of Babylon and presented themselves as rulers in the Mesopotamian and Persian traditions. Like other Hellenistic rulers, they claimed divinity.
The original capital of the empire was Seleucia on the Tigris, but it finally settled at Antioch in Syria. The empire’s vast size made complete centralization impossible. Drawing from the Persian Achaemenid political tradition of dividing the empire into satrapies, the early Seleucids divided their empire into large administrative districts mostly assigned to members of the royal family.
Another disadvantage of the size of the Seleucid Empire was that it faced problems on several frontiers, making it difficult for Seleucid kings to follow consistent foreign and military policies. After Seleucus the Seleucids lost much of their direct control over Iran and Bactria. Around the middle of the third century b.c.e. a new Greek kingdom arose in Bactria, while Iran fell to the Iranian Parthians.
Antiochus III (r. 223–187 b.c.e.), known as Megas or "the Great", reasserted Seleucid overlordship in this area in the late third century b.c.e., but his success proved short lived. In Asia Minor the Seleucids lost territories to invading Gauls and to a secession that led to the foundation of the independent Hellenistic kingdom of Pergamum, which would become a perpetual rival.
The Egyptian Ptolemies challenged Seleucid leadership in the Hellenistic Middle East. Antiochus expelled the Ptolemies from Palestine and Phoenicia, a long-standing area of contention between the two dynasties, after the Battle of the Panium in 200 b.c.e. However, the most fatal rival of Seleucia was the rising power of the Mediterranean, the Roman Republic.
Antiochus came into conflict with the Romans when he sought to expand into Asia Minor and Greece. After two defeats Antiochus agreed to the Peace of Apamea in 188 b.c.e., withdrawing from Europe and western Asia Minor and disbanding his navy and elephant force.
After Antiochus the Seleucid Empire was caught between the Romans in the west and the Parthians in the east. The empire also faced a major internal challenge from the population of Judaea.
Antiochus IV Epiphanes (r. 175–163 b.c.e.) was an avid promoter of Hellenic culture and of his royal cult. These policies provoked a revolt of the Jews, led by the Maccabees, who eventually managed to establish Judaea as an independent kingdom.
Antiochus IV was also forced into a humiliating withdrawal from Egypt, which he had reduced to a Seleucid satellite, when the Roman Senate sent an emissary demanding that he leave. The fact that Antiochus agreed to withdraw when faced merely by a representative of the Senate, not a Roman army, was particularly humiliating.
Antiochus died attempting to restore Seleucid power in the east. His death was followed by more defeats and turmoil within the Seleucid house between the descendants of Antiochus IV and his brother and royal predecessor, Seleucus IV Philopator (r. 187–175 b.c.e.). Mithridates I of Parthia took Babylon in 142 b.c.e. and captured the Seleucid ruler Demetrius II Nicator (r. 145–138, 129–126 b.c.e.) in 138 b.c.e.
There was a partial Seleucid recovery under Demetrius’s brother Antiochus VII when he advanced far into Parthian territory, but he was killed in battle in 129 b.c.e. The wife of both Demetrius and Antiochus, Cleopatra Thea from the Ptolemaic family, was the only Seleucid woman to rule under her own authority (r. 125–121 b.c.e.).
Seleucid power dwindled to Syria while the last Seleucids fought bitterly among themselves. Tigranes of Armenia briefly conquered the late Seleucid state, and finally the Roman general Pompey in 64 b.c.e. reduced Syria to a Roman province. The last Seleucid, Antiochus XIII Asiaticus (r. 69–64 b.c.e.) was murdered shortly thereafter.