Tokharistan

Tokharistan (formed from "Tokhara" and the suffix "-stan" meaning "place of" in Persian) is an ancient Early Middle Ages name given to the area which was known as Bactria in Ancient Greek sources.
Today, Tokharistan is fragmented between Uzbekistan, Tajikistan and Afghanistan, but it was recognized as a single unit by the Chinese Empire in the 7th and 8th century CE, as a region of the Protectorate General to Pacify the West (安西大都護府).
Names of Tokharistan.
Several languages have used variations of the word "Tokhara" to designate the region:
Ethnicities.
Several portraits of ambassadors from the region of Tokharistan are known from the "Portraits of Periodical Offering of Liang", originally painted in 526-539 CE. They were at that time under the overlordship of the Hephthalites, who led the embassies to the Southern Liang court in the early 6th century CE.
So-called "Tocharians" in the Tarim Basin.
The name of "Tocharians" was mistakenly applied by early 20th century authors to the Indo-European people of the Tarim Basin, from the areas of Kucha and Agni. These scholars mistakenly thought that these Indo-European people had originated in Tokharistan (Bactria), hence the name "Tocharian" they gave them. This naming has remained, although the Indo-European people of the Tarim Basin probably referred to themselves as "Agni", "Kuči" and "Krorän".
Geography.
Geographically, Tokharistan corresponds to the upper Oxus valley, between the mountain ranges of the Hindu-Kush to the south and the Pamir-Alay to the north. The area reaches west as far as the Badakshan mountains, south as far as Bamiyan. Arab sources considered Kabul as part of the southern border of Tokharistan, and Shaganiyan as part of its northern border. In a narrow sense, Tokharistan may only refer to the region south of the Oxus. The region used the East Iranian Bactrian language, which was current from the 2nd to the 9th century CE.
The most important city of Tokharistan was Balkh, which was at the center of the trade between Iran (the Sasanian Empire) and India.
The region of Tokharistan had been outside of Sasanian control for the three centuries preceding the Muslim conquest of Persia in 633-651 CE. During that time, Tokharistan was under the rule of dynasties of Hunnish or Turkic origin, such as the Kidarites, the Alchon Huns and the Hephthalites. At the time of the Arab conquest, Tokharistan was under the control of the Western Turks, through the Tokhara Yabghus.