Assamese literature its roots in the Eastern dialect. The modern Assamese period began with the publication of the Bible in Assamese prose by the American Baptist missionaries in 1819. The currently prevalent standard Asamiya has its roots in the Sibsagar dialect of Eastern Assam. As mentioned in Bani Kanta Kakati's "Assamese, its Formation and Development" (1941, Published by Sree Khagendra Narayan Dutta Baruah, LBS Publications, G.N. Bordoloi Road, Gauhati-1, Assam, India) – " The Missionaries made Sibsagar in Eastern Assam the centre of their activities and used the dialect of Sibsagar for their literary purposes". The American Baptist Missionaries were the first
Assamese language become infused with the eastern idiom, became the standard literary form in the nineteenth century, when the British adopted it for state purposes. As the political and commercial center shifted to Guwahati after the mid-twentieth century, the literary form moved away from the eastern variety to take its current form. Assamese is native to Brahmaputra Valley consisting of western and eastern Assam. It is also spoken in states of Arunachal Pradesh and Nagaland. Presence of Assamese script can be found in Rakhine state of present Myanmar. Pashupati temple in Nepal also have inscription in Assamese showing its influence and prosperity