The 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 in 1289. 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. Her description of them began:

Pray attend me while I tell my tale

Of Ala-eddin, the Old Man of the Mountain

Who by devious schemes, evil designs

And foul murders ruled the land.

No host of arms, no vast array

Of banners served this wicked lord.

They were but few - ruthless, reckless men

Who obeyed his cruel commands.

It went on to explain that they were defeated by Hulagu after a three-year siege. Their 250 faces were painted in the walls of the essentially eponymous Cave of Five Hundred Eyes, where they lived during that siege.

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