Probably we are talking about the mission “Control of the trade routes" or "Unification of Egypt". You just need to subdue of unite the tribes along the banks of the Nile. You don't need to touch tribes in the savannah and deserts. In the “Control of trade routes" mission you don't need to do something with the tribe of Seth in Ombos, because this tribe is too strong for you in the beginning. You can use the button "Go to" in the event window to see the next target to complete these missions.