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 realized as or as a retroflex approximant. Assamese and Sylheti are unusual among Eastern Indo-Aryan languages for the presence of the (which, phonetically, varies between velar () and a uvular () pronunciations, depending on the speaker and speech register), historically the MIA sibilant has lenited to and (non-initially). The derivation of the velar fricative from the coronal sibilant is evident in the name of the language in Assamese; some Assamese prefer to write or instead of or to reflect the sound change. The voiceless velar fricative is absent in the West Goalpariya dialects though it is found in lesser extent