Bactrian language
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.