The Seleucids were a hybrid civilization made up of a fusion of Mesopotamian, Syrian and Greek elements. They were ruled by a dynasty beginning with Seleucus I Nicator, who established his capitol at Seleucia. Seleucus I was murdered in 281 B.C.E.

A. Leo Oppenheim, Ancient Mesopotamia: Portrait of a Dead Civilization 414 (University of Chicago Press 1964 & 1977)