During the Missing Brother Quest in Assassin’s Creed Mirage, you will be given an Excavation site map and told to find where it is. Unlike many other quests in the game, there will be no objective marker that shows you where to go.
This map is a little difficult to read. The game doesn’t let you overlay it or view it with the main map. The map is also not exactly the same so it takes a bit of work. To save you some time, the image below shows the exact location. The observation point shows the oasis and the character pin shows where the site is.
The excavation site is quite easy to spot once you are in the area. The oasis will also give you a fast travel point. Once you walk into the site, the quest will update with the next part of the objective.