Assassin's Creed begins in 1191, when Altaïr Ibn-La'Ahad undertakes missions during the Third Crusade.
The game is set mainly in three historically significant cities: Masyaf, Jerusalem, and Acre. Altaïr serves the Assassin Brotherhood under Al Mualim, and his targets are connected to the conflict between the Assassins and the Knights Templar.
The year 1191 places the story after the 1187 Battle of Hattin and during the campaign associated with the Third Crusade. The game uses real leaders and locations, but its central conspiracy, advanced artifacts, and modern-day Animus storyline are fictional. A common mix-up is confusing the game's 1191 setting with the later historical events depicted in other Assassin's Creed titles.