In which historical setting does Assassin's Creed Origins take place?

Assassin's Creed Origins takes place in Ptolemaic Egypt.

The game is set mainly during the first century BCE, when Egypt was ruled by the Ptolemaic dynasty. Its protagonist, Bayek of Siwa, is a Medjay who becomes involved in events surrounding Cleopatra, Ptolemy XIII, and Julius Caesar. The story presents the formation of the Hidden Ones, the precursor organization to the later Assassins.

Players travel through cities, deserts, tombs, and settlements including Siwa, Alexandria, Memphis, and Cyrene. The setting draws on the political tensions of Egypt's final ruling dynasty and its relationship with Rome. Historical people appear alongside fictional characters and invented secret societies.

Ptolemaic Egypt is not the same as ancient Egypt's pharaonic Old Kingdom or New Kingdom. Cleopatra VII belonged to the much later Ptolemaic dynasty, a Greek-Macedonian ruling house that governed Egypt after Alexander the Great's conquest and the division of his empire.