Most of Assassin's Creed is set in 1191 during the Third Crusade.
The game follows the Assassin Altaïr Ibn-La'Ahad as he operates in the Holy Land during a conflict involving Crusader and Muslim forces. Its principal historical cities include Masyaf, Acre, Damascus, and Jerusalem. These locations are presented as connected hubs for missions, investigations, and assassination contracts.
The year is significant because the Third Crusade began after Saladin recaptured Jerusalem in 1187. Richard I of England, Philip II of France, and the Holy Roman Emperor Frederick Barbarossa were among the major European figures associated with the campaign, although the game's story uses fictional characters alongside historical settings and personalities.
The game is not a complete simulation of every event in 1191. Its fictional Templar conspiracy and the Assassin Brotherhood's activities are narrative inventions within a carefully researched medieval setting. The later prequel Assassin's Creed: Origins takes place centuries earlier, while Assassin's Creed II moves to Renaissance Italy.