D. the settlement of unpopulated areas
The empire began to weaken after Rome conquered Egypt and eventually collapsed sometime in the 300s CE. The Kingdom of Kush had two different capital cities. The first capital was Napata. Napata was located along the Nile River in Northern Kush.
Generally speaking, for a development such as this to be considered a civilization, there must be some form of government, which regulates to a certain extent the lives of the citizens.
One of the reasons was the blocked transportation routes, another was they were giving so many materials to the army to win they put aside their other business to focus on that
I'm not sure but I think it's coal mining
