Assassin's Creed uses the name Isu for the precursor civilization that existed before humanity.
The Isu are an advanced species who created humanity and built powerful artifacts, including the Pieces of Eden. Their civilization predates the historical eras shown in the games, but its technology and decisions shape the conflict between Assassins and Templars throughout the series.
Earlier games often called the Isu the “First Civilization” or the “Those Who Came Before.” Those phrases remain important descriptions and in-universe labels, but “Isu” is the specific name used in later series terminology. The Isu also appear under individual names, such as Minerva, Juno, and Jupiter. Their history is connected to the ancient catastrophe that devastated their civilization and left humans as the dominant species.