1) The Indus River valley was home to the ancient Harappan civilization around 2500 BCE, which thrived in isolation due to surrounding oceans and mountains. 2) From 1500 BCE, nomadic Aryan tribes entered India and gradually transitioned to a farming lifestyle, establishing a caste system and oral traditions that became Hindu scriptures like the Vedas. 3) The Mauyran Empire in 321 BCE and Gupta Empire from 310-400 CE represented golden ages of Indian civilization, with advances in mathematics, medicine, and infrastructure under emperors who promoted Buddhism and better lives for citizens.