Quite a lot of Nubian kingdoms, one of it was Kush, once served as a link for trade and barter because of their topography. They connected the Mediterranean world and Egypt to the to the Red Sea, as well as to the inner parts of Africa. Different products and even the beliefs of participating civilizations streamed forward and backward along the river for an extremely long period of time. Kerma, which is considered as the main Nubian kingdom, emerged not long after 2000 B.C.