of Syria, Lord of Asia, and other designations; the evidence for the Seleucid rulers representing themselves as kings of Syria is provided by the inscription of Antigonus son of Menophilus, who described himself as the "admiral of Alexander, king of Syria". He refers to either Alexander Balas or Alexander II Zabinas as a ruler. 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 and, from that point, continued to expand his dominions ruthlessly. Seleucus established himself in Babylon in 312 BC, the year later used as the foundation date of the Seleucid Empire. Babylonian War (311–309 BC) The rise of Seleucus in Babylon threatened the eastern extent of the territory of Antigonus I Monophthalmus in Asia. Antigonus, along with his son Demetrius I Poliorcetes, unsuccessfully led a campaign to annex Babylon. The victory of Seleucus ensured his claim of Babylon and legitimacy. He ruled not only Babylonia, but the entire enormous eastern part of Alexander's empire, as described by the historian Appian: 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 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