Transoxiana is an ancient name referring to a region and civilization located in lower Central Asia roughly corresponding to modern-day eastern Uzbekistan, Tajikistan, southern Kazakhstan and southern Kyrgyzstan. Geographically, it is the region between the rivers Amu Darya (Oxus River) to its south and the Syr Darya to its north.

It is known in Arabic as Mā Warāʾ an-Nahr (Arabic: ما وراء النهر‎, [ˈmaː waˈraːʔ anˈnahr] – ‘beyond the [Jayhūn] river’). The area had been known to the ancient Iranians as Turan, a term used in the Persian national epic Shahnameh, and to the Romans as Transoxiana (Land beyond the Oxus).

The region was one of the satrapies (provinces) of the Achaemenid dynasty of Persia under the name Sogdiana. It was defined within the classical world of Iran to distinguish it from Iran proper, especially its northeastern province of Khorasan—a term originating with the Sasanians—although early Arab historians and geographers tended to subsume the region within the loosely defined term “Khorasan” designating a much larger territory. The territories of Khwarazm, Sogdiana, Chaghaniyan, and Khuttal were located in the southern part of Transoxiana; Chach, Osrushana, and Farghana were located in the northern part.