Which Assassin's Creed game introduced the character Basim Ibn Ishaq as a central figure?

Assassin's Creed Valhalla introduced Basim Ibn Ishaq as a central figure.

Basim is a Hidden One from ninth-century Baghdad who travels to England and becomes involved in Eivor's story. He first appears as an experienced and enigmatic ally, but later revelations connect him closely to the series' ancient mythology and modern-day narrative.

Assassin's Creed Mirage, released later, makes Basim the playable protagonist and explores his earlier life in Baghdad. That relationship can cause confusion: Mirage is Basim's starring game, but Valhalla is where the character was first introduced to players.

Basim's presence also links the Viking-era narrative with the broader conflict between the Hidden Ones and the Order of the Ancients. His history is therefore important both to Valhalla's plot and to Mirage's origin story.