Kush began to fade as a power by the 1st or 2nd century AD, sapped by the war with the Roman province of Egypt and the decline of its traditional industries. ... Christianity began to gain over the old pharaonic religion and by the mid-sixth century AD the Kingdom of Kush was dissolved.
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With the loss of resources such as fertile soil and forests, Kush's military and economic power declined. New trade routes that bypassed Kush furthered its decline. Another contributor of Kush's downfall was Egypt's decline. Egypt was Kush's main trading partner, and because of Egypt's fall, bronze was difficult to come across.
