Seleucid Empire
Seleucus I Nicator was one of Alexander's generals who received a portion of the huge empire Alexander had carved out. He received huge expanses of land in Syria, Babylon, Anatolia, even as far out as India. When Perdiccas was killed in a political assassination by Ptolemy of Egypt, the empire that was barely held together then splintered apart. The Seleucid Empire quickly expanded, eventually taking parts of Thrace in the west and advancing past the Indus in the East.