Transoxiana is the now-largely obsolete name used for the portion of Central Asia corresponding approximately with modern-day Uzbekistan and southwest Kazakhstan. Geographically it means the region between the Amu Darya and Syr Darya rivers. When used in the present, it implies that one is talking about that region in the time prior to about the 8th century. This dividing line is used, as this was the point at which Islam came to dominate the region, after a century-long power struggle with Tang Dynasty China.

The name, however, is Greek, and literally means "Beyond the Oxus River", - an older name for the Amu Darya - which describes the region perfectly from the viewpoint of an ancient Greek. The name stuck in Western consciousness because of the exploits of Alexander the Great, who extended Greek culture into the region with his conquests of the 4th century BC; Transoxiana represented the uttermost northeastern point of the Hellenistic culture, and in fact kept a hybrid Greek/Indian/Chinese Buddhist culture, dubbed Serindian, until the Islamic conquest. During this time, when Transoxiana was cut off from the rest of Western culture by the Sassanid Empire, it is often called Sogdiana - a provincial name taken from early Persian, and used to distinguish it from nearby Bactria.

Transoxiana's major city and cultural center was Samarkand, while another was Bokhara. Both were on the southern fringes of Transoxiana, however (literally on the Oxus itself), and the majority of the region was dry but fertile plains.