The Seleucid Empire (ca. 330 - 150 BC)
When Alexander died abruptly in 323 BC, his generals split up his conquests, with one general, Seleucus, taking control of everything between Syria and Pakistan. Seleucus' empire was essentially Hellenistic, and many in the Persian ruling class began adopting Greek mannerisms to adapt to the new political reality, though this synthesis was a two-way street as newly established Greek and Macedonian aristocrats likewise adopted many local and Persian customs. This Greco-Iranian co-mingling is well symbolized by a statue of Heracles added to the Bisutun cliff face, site of King Darius' famous relief and trilingual inscription.
Ruling from the city of Seleucia in Mesopotamia, and later Antioch in Syria, the Seleucids presided over an empire stretching from the Mediterranean to modern-day India. They continued the Achaemenid satrapal system, leaving the Persian populations in Iran proper largely to their own machinations for the first century of Seleucid rule, as the dynasty was embroiled in conflicts in the west. It was not until the mid-late 3rd century BC that the Seleucids installed Greeks as satraps of Iranian provinces and campaigned in northeastern Iran and Central Asia. These incursions fostered resentment against the Seleucids, especially by hitherto independent Iranian tribes around the Caspian Sea. Led by the Parthians, these tribes launched a rebellion in 247 BC. Over the next two centuries, increasing pressure from the Parthians and devastating failures against Rome, Armenia, and Egypt gradually snuffed out Seleucid power.
Because of its Hellenistic influence and the self-consciously Greco-Iranian identity of its rulers, the Seleucid period is sometimes considered an interregnum between the "true" Persian empires and consequently understudied. However, it also permanently shaped subsequent dynasties, and left as its legacy both a Greek population and Hellenistic urban planning in the subsequent Parthian period.
