The research notes of western explorers are the earliest extant documents on the Bai language, the Chinese being not terribly interest in linguistic research at the time. While linguistics was quite immature at the time, their notes remain valuable for understanding the Bai language.
Terrien de Lacouperie falsely notes in his book on the languages of China that Bai was of Mon-Khmer origin:
The Min-kia Tze 民家子, or Peh-jin 白人,
now intermingled with the other population of the neighbouring region
of Tali-fu in C. W. Yunnan and the S.E. of the Province, claim to have
come from S. Kiangsu near Nanking. They are much mixed in race, and
their language bears the same testimony; we have a vocabulary of 110
words, including numerals, published by Father Desgodins, and another series of numerals by the late Francis Gamier. Chinese, Mosso, Lolo and Tibetan words have been adopted instead of the
original vocables, but the Mon character of the language is still
recognizable in many words, and the positions of the genitive and of the
adjective (2 4) are in accordance with this indication.
Categorical particles are apparently used not as prefixes but as suffixes only, somewhat us in Chinese. K'u, ICou seem to be attached to all names of things high or large, de appears at the end of words for animals, and qualities. All the numerals as given by Gamier are followed by the particle -pe, which appears in the vocabulary as suffix of a few words, gni-pe ' sun,' uan-la-pe ' soul,' etc.
Col Davies in his book on Yunnan affirms the Lacouperie's views:
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