The ruins of the “bronze age” Indus Valley Civilization are now mostly in the Great Indian Desert, and the ruins of once great Sumer and Akkad too now in the desert of southern and central Iraq, plus Canaanite ruins in the Levant where now are deserts (such as Arad in the Negev desert), so obviously the climate changed dramatically to have caused the abandonment of those sites, within about a hundred years, the ending of the Ice Age when the ocean had cooled to about today’s temperatures.
