Help please

[d'Arthez]

Yes, you can still conquer that province. Just do not tear down that building.

[Fluvius Camillus]

It's Tuat, I have always conquered it when I attack Carthage. The victory building is there and you shoul not mess with it, then everything is fine. It is also possible to build any government there. Pre-1.0 versions of Tuat included even more victory buildings for all factions.

You can not conquer the whole Sahara though, Terhazza was unreachable.

~Fluvius

[Ankhenaten]

Yes, as long as you don't mess with that building. Most of the victory buildings were placed by the designers in Terhazza, but they ran out of room and placed one in Tuat. Just ignore it.