Geography and climate both played significant roles in the settlement and development of ancient Indian civilization. The first notable geographical feature is the Himalayan Mountains located in the northern portion of the Indian subcontinent that severs India from the rest of Asia; preventing hostile invading forces and immigration into the subcontinent. The second feature, the two rivers of Ganges and Indus are the foundations of early Indian civilization that make their land livable. The Ganges river flows southeast through a fertile valley, providing the necessary water for a successful harvest. The Indus River flows southwest across a drier plain, in turn affecting how farming was achieved. Because of the drier land area, Ancient Indians were forced to irrigate to obtain the needed stock of food to distribute among their peoples, much less a emergency surplus. The last major geographical feature was the Khyber Pass -- the only easily traversed path connecting Asia and India near Kabul.
Climate was an ingredient in early Indian civilizations for several reasons. Monsoons, winds that mark the seasons, are one of the most immediate. The first monsoon of the season blows from North to Northeast periodically during November through March. Little rain is present during this monsoon, however what precipitation does fall, it falls on the Northern slope of the Himalayas. During mid-June through October a second monsoon indicates the 'Wet Season' - a.k.a. - the southwest monsoon. Following the southwest monsoon, heavy rains fall in it's wake (however sparse rainfall falls on the Western Ghats, the heaviest rainfall occurs over the Ganges Valley and the Eastern Himalayan Mountains). The timing of these winds are critical; too little or too late rainfall results in an unsuccessful harvest, yet too much or an extended period of rainfall causes flooding along the country side. Temperatures also play a significant role in how Indian's settled the land in ancient times. The ideal area - the Deccan plateau - had mild temperatures in the summer opposed to the blistering heat of the western Ghats and valleys which could climb up to one-hundred twenty degrees Fahrenheit.
Also, another reason the geographical importance of India is held so highly is because if the disappearances of the first Harrapan civilizations in Mohenjo Daro. Historians and researches have many theories, yet they all relate to climate, geographical, and regional issues however there is no solid evidence to prove or reject any of their hypothesis. Some of the more common are; Harsh monsoons causing a type of violent weather pattern, evidence of an earthquake has been speculated, intense flooding of the Indus and Ganges Rivers, hostile invading forces, and other reasons have been thrown around.