Indus Valley Civilization By karimandraoos Period: 3000 BCE to 2600 BCE The rise of the great Indian cities of Mohenjo Daro and Harappa. 2500 BCE Well planned cities flourished in the valley 2500 BCE Earliest use of the Indus Script 2000 BCE Indus valley farmers began to abandon their land Period: 2000 BCE to 1500 BCE Newcomers from the north entered the valley 1500 BCE Aryans began to migrate into the Indus Valley. 800 BCE People of northern India had learned to make tools and weapons out of iron 500 BCE There was a strict division of classes 320 The Gupta dynasty rose to power