As the result of language contact in the northern Tibetan region, one variety
of the Mongolic language Monguor (ISO 639-3: MJG) realizes prosodic
accent as a rising pitch contour. Furthermore, a small number of homophones
have come to be distinguished by tonal contour. Although at least two Turkic
and Mongolic languages have occasionally copied the most salient tonal
features of some Chinese loanwords, this is the first known example of both
distinctive pitch contrasts in native lexemes, as well as default prosodic
accent at the utterance level. Such an incipient tonal system offers insight into
the relationship between often-contested types of prosodic accent as well as
the effects of intensive language contact.


http://kuscholarworks.ku.edu/dspace/bitstream/1808/7055/1/Dwyer2008_TonogenesisSEMonguor.pdf