India and its surrounding countries are so similar in culture and climatic conditions that the region is sometimes called the Indian sub-continent. In ancient times the geography of India was a little different than what it is today. In the northern part of India stand the Himalayan Mountains and the Hindu Kush stand in the North West. The southern region of India is surrounded by three bodies of water. They are the Arabian Sea to the south west; the Indian Ocean on the southern side and to the southeast lay the Bay of Bengal.
In ancient times, India was much more extended to the North West and west (consisting of parts of modern Pakistan and Afghanistan). The Himalayas lay to the north as they are today. In ancient period there were many other rivers besides the preset ones. The most important of them was River Saraswati, which is not traceable now. The geography of India is one of great extremes, encompassing desert, mountains, forest, and jungle. All of these environments are susceptible to unpredictable periods of flood, drought, and monsoon.
Although India may bear some of the most extreme geological and climatic features, these difficult conditions were also a great asset to the development of India's early civilizations. The Himalayas provided a great deal of protection from nomadic and military invasions from the north, and other mountain ranges provided similar protection in the west and east. The water ways of the Indus valley provided an excellent source for trade and commerce all through India's history.