1) India is geographically diverse, with some areas receiving heavy rainfall while others are dry. Three key regions are the Himalayan mountains, the Indus and Ganges river valleys, and the Deccan plateau. 2) The ancient cities of Mohenjo-Daro and Harappa in modern-day Pakistan show evidence of careful urban planning, with structures made of fired mud bricks and citadels towering above plains. 3) The Aryans entered India from the northwest as part of a widespread migration that transformed many ancient societies. They brought Sanskrit language and composed the Rig Veda hymns praising Aryan gods.