Roughly shaped like a bird with wings stretching along the length of the Brahmaputra river, Assam is the central state in the North-East Region of India and serves as the gateway to the rest of the Seven Sister States. The land of red river and blue hills, Assam comprises three main geographical areas: the Brahmaputra Valley which constitutes the expansive wingspan, the Barak Valley extending like a tail, and the intervening Karbi Plateau and North Cachar Hills. Assam shares its border with Meghalaya, Arunachal Pradesh, Nagaland, Manipur, Tripura, Mizoram and West Bengal; and there are National Highways leading to their capital cities. It also shares international borders with Bhutan and Bangladesh. In ancient times Assam was known as Pragjyotisha or Pragjyotishpura, and Kamarupa.