M. assamensis
This taxon occurs in Bangladesh, Bhutan, southwestern China (Guangxi, Guizhou, Tibet and Yunnan), northeastern India (Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura, Uttar Pradesh, and West Bengal), Lao PDR, Myanmar, Nepal, northwestern Thailand, and northern Viet Nam. It is found from central Nepal east into northern Myanmar and southeast through southernmost China to the upper Mekong in Tibet, and in the east into southern Guizhou to Hoi Xuan in Viet Nam and Thateng in Lao PDR; the range continues south through the Myanmar/Thailand border ranges as far as Chongkrong, as well as to the Sunderbans in Bangladesh. There is a gap in northeastern India between the two main population pockets, specifically between central Bhutan and the south side of the Brahmaputra; the east bank of its upper course, the Dhibang, marks the division between the two subspecies (Groves 2001).

M. a. assamensis
This taxon occurs in Bhutan, southwestern China (Guangxi, Guizhou, Tibet, and Yunnan), northeastern India (Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura), northern Lao PDR, Myanmar, northwestern Thailand, and northern Viet Nam. Found north along the Dihang River and its Tibetan tributary the Ngagong (Groves 2001).

M. a. pelops
This taxon occurs in Bangladesh, Bhutan, northern India (Assam, Sikkim, Uttar Pradesh and West Bengal) and Nepal. Found from central Nepal through Sikkim and northernmost West Bengal into central Bhutan and the Sunderbans; apparently occurs as well north of the Himalayan crest in the Bhong Valley (Groves 2001).