Seleucus I Nicator

After the death of Alexander, Seleucus established control over Babylon and the eastern satrapies. He founded the Seleucid Empire, which stretched from Anatolia to India, and adopted the title of king. This marked the beginning of the Hellenistic period in the East.

Seleucus I Nicator fought against Antigonus I Monophthalmus at Ipsus. The allied forces of Seleucus, Lysimachus, and Cassander defeated Antigonus, who was killed. This battle solidified the division of Alexander's empire, with Seleucus gaining control of Syria and Mesopotamia.

Seleucus I founded the city of Antioch on the Orontes River, which became the capital of the Seleucid Empire. The city grew into a major center of Hellenistic culture, trade, and politics, rivaling Alexandria in importance.

Seleucus I was assassinated by Ptolemy Ceraunus, a son of Ptolemy I, while campaigning in Thrace. His death ended the last major Diadochi conflict and left the Seleucid Empire to his son Antiochus I, who faced challenges from within and without.