In Assassin's Creed Origins, Bayek of Siwa's story is set in Ptolemaic Egypt.
The game takes place in the first century BCE, during the reign of Cleopatra VII and the final period of the Ptolemaic Kingdom. Bayek is a Medjay from Siwa who investigates a conspiracy affecting his family and gradually becomes involved in the origins of the Hidden Ones, the organization that later develops into the Assassin Brotherhood.
Origins presents Egypt as a politically divided land shaped by the rivalry between Cleopatra and Ptolemy XIII, with Roman intervention led by Julius Caesar. Locations include Alexandria, Memphis, Cyrene, and the Giza plateau. The game combines historical people and places with fictional conspiracies and the series' Isu mythology.
This period should not be confused with ancient Egypt's earlier pharaonic eras. The pyramids are already ancient within the game, while the political world is much closer to the rise of Roman power in the Mediterranean.