Why do traditional costumes of the Tibeto-Burman people of northeastern India look different from those elsewhere?

Comparison of traditional costumes of Tibeto-Burman peoples in Northeast China (first three pictures) and Tibeto-Burman peoples in Southeast Asia and East Asia (last three pictures). I feel that the headdress looks very distinctive and reminds me of some Austronesian peoples, such as some peoples in Taiwan and Indonesia. East and Southeast Asian peoples such as the Burmese, Yi people, and Karen people do not have headdresses, but wear hats instead…