Indian history, like world history, is divided into three periods: ancient, medieval, modern. Ancient period starts from Indus Valley Civilization down to the eighth century. In the intervening period Aryans came and introduced the caste system in which Brahman stood at the apex and Shudra at the bottom, and in between stood Chattari and Vaish. Aryans were a pastoral society who took to cultivation in course of time. Wars and peace among them went...