was called the "oxus" by the ancient greeks. in ancient times, the river jayhan was regarded as the boundary between irān and tūrān. the river jayhan drainage lies in the area between the former empires of genghis khan and alexander the great, although they occurred at much different times. one southern route of the silk road ran along part of the jayhan river northwestward from termez before going westwards to the caspian sea.