Tokharistan
Following the settlement of the Yuezhi (referred to by the Greeks as Tókharoi), the general area of Bactria came to be called Tokharistan. The territory of Tokharistan was identical with Kushan Bactria, including the areas of Surkhandarya, Southern Tajikistan and Northern Afghanistan.
The first literary mentions of Tokharistan appear at the end of the 4th century in Chinese Buddhist sources (the Vibhasa-sastra). However, the first mention of the Tókharoi appear much earlier, in the 1st century BC, when Strabo mentions that "the Tókharoi, together with the Assianis, Passianis and Sakaraulis, took part in the destruction of the Greco-Bactrian kingdom" in the second half of the 2nd century BC. Ptolemy also mentions a large Tokharian tribe in Bactria, describing the central role of the Tokharians among other tribes in Bactria. (Through an accident of naming, the term "Tocharian" now commonly refers to a branch of Indo-European languages spoken in the Tarim Basin between the 3rd and 9th centuries AD, and quite distinct from the Bactrian language spoken by the Tókharoi.)
From the 1st century AD to the 3rd century AD, Tokharistan was under the rule of the Kushans. They were followed by Sassanides (Indo-Sassanids). Later, in the 5th century, it was controlled by the Xionites and the Hephthalites. In the 7th century, after a brief rule under the Turkish Khaganats, it was conquered by the Arabs and then the Mongols and much later, by the Russians.
Read more about this topic: Bactria