Wikipedia
Chorasmia (satrapy)
Chorasmia (Old Persian Uvârazmiya) was a satrapy of the Achaemenid Empire in Persia. Chorasmia had become part of the Achaemenid Empire before 522, and it seems to have been ruled by the satrap of Parthia.
By the time of the Persian king Darius III, it had become an independent kingdom. Its king, Pharasmanes concluded a peace treaty with Alexander the Great in the Winter of 328/327. Chorasmia approximately corresponds to the modern-day region of Khwarezm.