Which ancient civilization is represented by the Isu in the Assassin's Creed series?

The Isu are the fictional First Civilization in the Assassin's Creed series.

They are an advanced precursor species that existed on Earth before modern humans. The Isu created powerful artifacts, including Pieces of Eden, and used technology that later cultures often interpreted as magic or divine power. Their civilization was eventually devastated by a solar flare and by conflict with humanity.

The First Civilization is not the same as a real-world empire or culture. The series gradually reveals its history through genetic memories, hidden sites, inscriptions, and modern-day investigations. Individual Isu figures such as Minerva, Juno, and Jupiter appear across the mythology. The term “precursors” is also used in some series discussions, but “First Civilization” is the canonical name most directly associated with the Isu as a group.