The main story of the original Assassin's Creed takes place in 1191.
The game is set during the Third Crusade, a period of conflict involving European Crusaders, Muslim forces, and political powers in the eastern Mediterranean. Its historical cities include Jerusalem, Acre, and Damascus. The player controls Altaïr Ibn-La'Ahad, an Assassin operating under the direction of the Order's leadership.
The year 1191 places the story during the reign of Richard I of England, commonly called Richard the Lionheart, who participated in the Third Crusade. The game uses real historical figures and events as a foundation, but its secret-war narrative is fictionalized. Altaïr's targets are presented as influential figures whose deaths affect the balance between rival factions.
A common mix-up is confusing the game's setting with the beginning of the Crusades. The First Crusade began in 1096, almost a century earlier. The original game's date also predates the Renaissance setting of later entries such as Assassin's Creed II.