Kamarupa
Kamarupa (Assamese: কামৰূপ ৰাজ্য), also called Pragjyotisha, was the first historical kingdom in Assam that existed between 350 and 1140 CE i.e. for almost 800 years. Ruled by three dynasties from their capitals in present-day Guwahati and Tezpur, it covered the entire Brahmaputra river valley and, at times, North Bengal and parts of Bangladesh.
Read more about Kamarupa.