Osrušana or Ustrushana was a former Iranian region in Transoxiana, home to the Principality of Ushrusana, an important pre-Islamic polity of Central Asia. Oshrusana lay to the south of the great, southernmost bend of the Syr Darya and extended roughly from Samarkand to Khujand. The capital city of Oshrusana was Bunjikat. The exact form of the Iranian name Osrušana is not clear from the sources, but the forms given in Hudud al-'alam, indicate an original *Sorušna.

Transoxiana or Transoxania is the Latin name for the region and civilization located in lower Central Asia roughly corresponding to modern-day eastern Uzbekistan, western Tajikistan, parts of southern Kazakhstan, parts of Turkmenistan and southern Kyrgyzstan. The name was first coined by Alexander the Great in the 4th century BC when Alexander's troops were able to conquer the region. The region may have had a similar Greek name in the days of Alexander the Great, but the earlier Greek name is no longer known. Geographically, it is the region between the rivers Amu Darya to its south and the Syr Darya to its north.