Bactria is the ancient name of a historical region covering the modern-day flat regions that straddle present-day Afghanistan, Pakistan, and Tajikistan.

Bactria is one of the ancient civilizations of Iranian peoples.

It is located south of the Pamir Mountains and the Amu Darya, surrounding the district of Gandhara (said to be its "crown jewel") to its south.Bactria is the birthplace of Zoroastrianism, and later also hosts Buddhism before becoming Muslim after the arrival of the Rashidun and the Umayyad Caliphates in the seventh century.

Bactria is also sometimes referred to by the Greeks as Bactriana.