the kingdom of nubia (kush) in North africa absorbed the culture and tradition of the civilization of?

The kingdom of Nubia in North Africa absorbed the culture of African peoples in the South, but in the North, their culture was very close to the Ancient Egypt one. They had a similar way of government, religion (they both strongly believed in the afterlife), they built pyramids (even though Kush Pyramids were smaller than Egyptians), worshiped Egyptian gods and mummified the dead. The ruling and upper class of Kush, actually, considered themselves Egyptians.