 At the height of its power, the Empire included central Anatolia, Persia, the Levant, Mesopotamia, and what is now Kuwait, Afghanistan, and parts of Pakistan and Turkmenistan.The Seleucid Empire became a major center of Hellenistic culture – it maintained the preeminence of Greek customs where a Greek political elite dominated, mostly in the urban areas.The Greek population of the cities who formed the dominant elite were reinforced by immigration from Greece.