The Burmese-Lolo, Tai-Kadai, Miao-Yao and Chinese languages form a loose Sprachbund in Southwest China with hundreds of languages coexisting and assimilating to each other. Shared language patterns include grammaticalized prepositions and aspect particles. Meanwhile individual languages showcase highly idiosyncratic properties not paralleled in any genetically or areally related language. In his fieldwork, the author encountered a range of rare sound phenomena: a bilabial trill in Nuosu, eleven retroflexive consonants in Neasu, five plain versus nasalized vowel pairs in Xong and nine contrastive tones in Kam two of which are undulated.