Siwa is the Egyptian city where Bayek's early story in Assassin's Creed Origins begins.
Bayek is a Medjay, a protector and lawkeeper, from the Siwa Oasis. The opening chapters establish his personal mission there before the wider adventure takes him across Ptolemaic Egypt. Siwa therefore functions as both a geographic starting point and an important part of Bayek's identity.
Origins is set in the first century BCE, during the reign of Cleopatra and the political struggle involving Ptolemy XIII. The game eventually visits major places such as Alexandria, Memphis, and Cyrene, but those are different locations from Bayek's home oasis.
The title explores the formation of the Hidden Ones, the organization that later develops into the Assassin Brotherhood. Its setting and story are designed as an origin narrative for the series' fictional order, while the historical background draws on real Ptolemaic Egypt.