Ancient Greece, that is.
The title is reportedly well into development and is targeting a release in 2019 for PC, PS4, and Xbox One.
Even though just a rumor, the information comes from Liam Robertson of Comicbook.com, who correctly leaked details Assassin’s Creed Origins, while still in development. So he has a solid source, but still a rumor, none-the-less.
[Source: Comicbook.com]