About 2 million years ago man lived in the foothills of Himachal Pradesh, viz in the Bangana valley of Kangra, Sirsa valley of Nalagarh and Markanda valley of Sirmour. The foothills of the state were inhabited by people from Indus valley civilization which flourished between 2250 and 1750 B.C. People of Indus valley civilization pushed the original inhabitants of Ganga plains who were known as Kolorian people towards north. They moved to the hills of Himachal Pradesh where they could live peacefully and preserve their way of life.
In the Vedas they have been referred to as Dasas, Dasyus and Nishadas while in later works they have been called Kinnars, Nagas and Yakshas. The Kols or Mundas are believed to be the original migrants to the hills of present day Himachal.
The second phase of migrants came in the form of Mongoloid people known as Bhotas and Kiratas. Later on came the third and most important wave of migrants in the form of the Aryans who left their Central Asian home. These laid the base of history and culture of Himachal Pradesh.