Assassin's Creed Origins

For this achievement you must simply enter all of the different regions of the map. You don’t have to synchronize every viewpoint for this achievement, though it is strongly recommended you do this anyway as it will make your life a LOT easier later on.

You can technically do this at any time in the game, just note that some of the later regions in the game have enemies that will kill you instantly!

Once every region on the map as been defogged, the achievement will unlock.