(historical) The territory governed by a satrap; a province of any of several ancient empires of West Asia (specifically, of the Median or Achaemenid empires or certain of their successors, including the Sasanian Empire and Hellenistic empires).
1951, W. W. Tarn, The Greeks in Bactria and India, Cambridge University Press, 2nd Edition, Digital printing 2010, page 1,
The Seleucid empire in its turn was still, in outward shape, very much the empire of Persia under different rulers; the great satrapies still remained, their military nature emphasised by the governor of a satrapy being no longer called satrap but strategos, 'general'.