Hashashin

Hashashins were a group of what Marco Polo called "evil men" who were put to death some twenty years prior to Polo's meeting with the First Doctor. They were so named because they used hashish. They had an armed conflict with the Mongol leader Hulagu, and lost, their defeat the subject of an elaborate story performed by Ping-Cho, which connected the Hashashin to Ala-eddin of Persia. Their 250 faces were painted in the walls of the essentially eponymous Cave of Five Hundred Eyes, where they once lived.

Ian told Susan that the English word assassin was derived from this group. (TV: "Five Hundred Eyes")