Question

What caused the decline of ancient Egypt's old kingdom ?

Answer 1

Egypt thus fell easy prey to the expanding Persian empire in 525 BC, remaining under their dominion for over a century. National rule was revived between 404 and 342 BC, but the various regimes (the 28th, 29th and 30th dynasties) were riven by in-fighting, and the Persians reasserted their power in 342 BC.