Which Assassin's Creed game is set in Baghdad and follows Basim before he joins the Hidden Ones?

The Assassin's Creed game set in Baghdad that follows Basim before he joins the Hidden Ones is Assassin's Creed Mirage.

Mirage is a prequel to Assassin's Creed Valhalla and centers on Basim Ibn Ishaq during his early life in ninth-century Baghdad. Before becoming a Hidden One, Basim is a young street thief in Anbar who dreams of a different life. His path changes when he encounters the Hidden One Roshan, who becomes his mentor.

The game focuses on Basim's progression through the Hidden Ones and his missions across Abbasid-era Baghdad. Its design deliberately emphasizes stealth, investigation, social infiltration, and parkour, recalling the structure of earlier Assassin's Creed games more closely than the large role-playing systems of several recent entries.

Mirage is sometimes mistaken for Valhalla because Basim is an important character in both. The distinction is chronological: Valhalla presents Basim during the Viking Age, while Mirage depicts his earlier years in Baghdad before his journey to England.