Zoroastrism was most probably the most widespread religion in pre-Islamic Afghanistan. However, parts of southern Afghanistan were parts of the Mauryan Empire 305 BCE - 185 BCE. Emperor Asoka was most prominent figure for spread of Buddhism on his empire's territory. Two Rock Edicts, containing Asoka's principles and statements survive in regions of Kandahar and Laghman. These edicts in Afghanistan were written in Greek. In 185 BCE the Sunga Coup happened: Pusyamitra Sunga murdered last Mauryan ruler (Brhadrata) and instituted his own (Sunga) Empire. Sunga Empire promoted Hinduism and persecuted Buddhists. It is up to debate whether Buddhism in Afghanistan was eliminated after 185 BCE.

In 180 BCE Demetrius I of Bactria conquered parts of India. However this Greco-Bactrian Kingdom was overthrown by Central Asian nomads, who formed the Kushan Empire in ~135 BCE; they finally overthrew the Greco-Bactrian Kingdom in 125 BCE. The Kushan Empire was instrumental in spread of Buddhism through Central Asia and China. Two largest statues of Buddha were carved in Afghanistan (in Bamyan Mountains). The statues were 175 and 120 ft tall, and survived until 2001 (when they were destroyed by the Taliban). Kushan koins had icons of various deities, including Buddhist figures, on their coins.