Which religion do most citizens of Afghanistan follow?

Afghanistan is an Islamic emirate, in which most citizens follow Islam. As much as 90% of the population follows Sunni Islam.

The religion Zoroastrianism is believed by some to have originated in what is now Afghanistan between 1800 and 800 BCE, as its founder Zoroaster is thought to have lived and died in Balkh while the region at the time was referred to as Ariana.

Mainly concentrated in eastern and southern regions of present-day Afghanistan, early Indo-Aryan inhabitants (between 2000 and 1500 BCE) were adherents of Hinduism.

Following Alexander the Great's conquest and occupation in the 4th century BC, the successor-state Seleucid Empire controlled the area until 305 BC when they gave much of it to the Indian Maurya Empire as part of an alliance treaty. The Mauryans brought Buddhism from India and controlled parts of southern and eastern Afghanistan until about 185 BC when they were overthrown.

In the 7th century, the Umayyad Arab Muslims entered into the area now known as Afghanistan. A large number of the inhabitants of the region of northern Afghanistan accepted Islam through Umayyad missionary efforts. Since the 9th century, Islam has dominated the country's religious landscape.

Once the Soviet-backed Marxist-style regime (1979) came to power in Afghanistan, the People's Democratic Party of Afghanistan (PDPA) moved to reduce the influence of Islam.