In the time of the pharoahs Egypt was divided into the Black Land of the Nile Valley and the Red Land of the desert. Most of the desert near the valley is a reddish colour. You can tell where the antiquities were by a slight white tinge to the desert where the stone chips still cover the sand after the limestone was cut up. The black soil of the valley used to be replenished by the silt from the Nile during the yearly flood. Now it is replenished by the addition of the manure from the water buffalo, silt dug out of the canals during dredging and the careful rotation of the crops by the farmers.