Answer:
The group that became the most powerful following the withdrawal of Russian troops from Afghanistan in 1989 was the Taliban.
Step-by-step explanation:
The Taliban is a fundamentalist Islamic nationalist movement that spread in Pakistan and especially Afghanistan since 1994 and which ruled Afghanistan between 1996 and 2001. The movement developed among members of the Pashtun ethnic group, but also included many non-Afghan volunteers from the Arab world, as well as from Eurasia and South and Southeast Asia.
For nearly two decades, its leader was Mohammed Omar, considered one of the most influential jihadists in the world. He led the fight to establish the Taliban as the main political and military force in Afghanistan in the 1990s, and then led the insurgency against Western troops in Afghan territory. When killed, in 2013, he was succeeded by Akhtar Mohammad Mansour. This, however, was also killed in an American air raid in May 2016. He was succeeded by Mawlawi Hibatullah Akhundzada, who took over, on May 25, full operational control of the group.