The Persian occupation of
Egypt
extended over 121 years , beginning from Cambyses , son of Korush . Cambyses stayed in Egypt for three years , during which he sent an expedition to the Oasis of
Siwa
to get revenge of its priests who issued a prophecy predicting that Cambyses will lead a short life with a bad destiny in Egypt . The sandstorms swallowed his army , which is still buried in the Sahara Desert . Cambyses sent another expedition to
Nubia
but Napata princes defeated the Persian Army and Cambyses lost his mind . He died in Syria , on his way back to his country .