Al-Qaeda grew out of the Services Office, a clearinghouse for the international Muslim brigade opposed to the 1979 Soviet invasion of Afghanistan. In the 1980s, the Services Office—run by bin Laden and the Palestinian religious scholar Abdullah Azzam—recruited, trained, and financed thousands of foreign mujahadeen, or holy warriors, from more than fifty countries. Bin Laden wanted these fighters to continue the “holy war” beyond Afghanistan. He formed al-Qaeda around 1988.

Source:  Council on Foreign Relations