Assassin's Creed Origins is set during the reign of Ptolemy XIII.
The game begins in 49 BCE, when Ptolemy XIII is pharaoh of Egypt during a struggle for power with his sister Cleopatra VII. Bayek of Siwa, the protagonist, becomes involved in the political and personal conflicts surrounding this crisis while investigating the masked Order of the Ancients.
Ptolemy XIII ruled as a member of the Ptolemaic dynasty, a Macedonian Greek royal house that governed Egypt after the death of Alexander the Great. His conflict with Cleopatra eventually drew in Julius Caesar and Roman forces, all of whom appear in the game's historical narrative.
The title “pharaoh” can make players associate the setting with much earlier Egyptian rulers such as Ramesses II. Origins instead depicts Hellenistic Egypt near the end of the Ptolemaic period. Its fictional origins story links the Order of the Ancients to the later Assassin Brotherhood.