Bactria

Bactria (from Βακτριανή, the Hellenized version of Old Persian Bāxtriš; Elamite ba-ak-ši-iš, Persian and Pashto as باختر Bākhtar or Pākhtar; Tajik: Бохтар; Chinese 大夏 Dàxià) is the ancient name of a historical region located south of the Amu Darya and west of Gandhara. It was a part of the eastern periphery of the Iranian world, now part of Afghanistan. Once Zoroastrian, this region subsequently hosted Buddhism before becoming Muslim after the arrival of the Rashiduns and Umayyads in the 7th century. Bactria was also sometimes referred to by the Greeks as Bactriana.

Read more about Bactria:  Geography, Tokharistan, Onset of Islam, Bactrian People