Chorasmia was a satrap

Satrap

Satrap was the name given to the governors of the provinces of the ancient Median and Achaemenid Empires and in several of their successors, such as the Sassanid Empire and the Hellenistic empires....

y of the Achaemenid Empire

Achaemenid Empire

The Achaemenid Empire , sometimes known as First Persian Empire and/or Persian Empire, was founded in the 6th century BCE by Cyrus the Great who overthrew the Median confederation...

. Chorasmia had become part of the Achaemenid Empire before 522, and it seems to have been ruled by the satrap

Satrap

Satrap was the name given to the governors of the provinces of the ancient Median and Achaemenid Empires and in several of their successors, such as the Sassanid Empire and the Hellenistic empires....

 of Parthia. By the time of Darius III, it had become an independent kingdom. Its king, Pharasmanes

Pharasmanes

Pharasmanes or Parsman may refer to several monarchs:*Pharasmanes I of Iberia*Pharasmanes II of Iberia*Pharasmanes III of Iberia*Pharasmanes IV of Iberia*Pharasmanes V of Iberia*Parsman VI of Iberia...

 concluded a peace treat with Alexander the Great in the Winter of 328/327. Chorasmia approximately corresponds to the modern-day region of Khwarezm

Khwarezm

Khwarezm, or Chorasmia, is a large oasis region on the Amu Darya river delta in western Central Asia, which borders to the north the Aral Sea, to the east the Kyzylkum desert, to the south the Karakum desert and to the west the Ustyurt Plateau...

.