Assassin's Creed Mirage primarily depicts the year 861 in ninth-century Baghdad.
The game follows Basim Ibn Ishaq before he becomes a prominent Hidden One. Its historical setting is Abbasid Baghdad, especially during the period when the city was a major center of scholarship, trade, administration, and political power. The story begins in 861 and uses that date to place Basim's personal journey within the Abbasid period.
Mirage's Baghdad is a reconstructed historical setting rather than a modern city map. Important locations and institutions draw on the city's role during the Islamic Golden Age, while the Assassin and Templar conflict remains fictionalized through the series' Hidden Ones and Order of the Ancients mythology.
The year can be confused with the broader Abbasid era or with the dates associated with other Assassin's Creed games. Mirage is specifically centered on 861, whereas Origins takes place centuries earlier in Ptolemaic Egypt and Valhalla moves into ninth-century England.