Kafiristan was a Middle Eastern country near the Soviet Union.
In 1989, Sayf Udeen was the prince of the country. The Seventh Doctor, Raine Creevy and Ace defeated the Metatraxi there. (AUDIO: Crime of the Century)
Kafiristan ("land of the infidels") was a real historical region that became known as Nuristan ("land of illumination") in 1895 and is now a province of Afghanistan.