Based on unearthed manuscripts, this paper studies the history of voiceless nasals and liquids in old Chinese phonology. It shows that there was a set of aspirated voiceless nasals and liquids and a set of unaspirated voiceless nasals and liquids in the common language of Shang and Western Zhou Dynasty. The aspirated voiceless nasals and liquids were *(m) under circle (h)-, *(n) under circleh-, *(eta) over circle (h)-, *(l) under circleh-, *(l) under circle hj-, *(r) under circle-, and the unaspirated voiceless nasals and liquids are*(m) under circle-, *(n) under circle-, *(eta) over circle-, *($) over circlej-, *(l) under circle-, *(r) under circle-. In Chu dialect, the voiceless nasals and liquids continued to exist in Warring States period. They were *(m) under circle, -*(n) under circle-, *(eta) over circle-, *(l) under circle-, *(m) under circle (h)-, *(n) under circleh-, *(n) under circle hj-, *(l) under circleh-, *(r) under circleh-. Voiceless nasals and liquids were preserved in the Qin dialect in Warring States period and the common language in late Warring States and early Han Dynasty. They were *(m) under circle-, *(eta) over circle-, *(eta) over circleh-, *(eta) over circlej-, *(l) under circle-, * (l) under circleh-, *(l) under circle hj-, *(r) under circle-, *(r) under circleh-. In ancient Chinese, both nasal and liquid were trisection. Some voiceless nasals and liquids probably came from complex consonants such as *hN-, *hr-, *hl-, and so on. Some voiceless nasals and liquids became aspirated voiceless obstruent initials or unaspirated fricatives respectively. The voiceless nasals and liquids are difficult to trace after the late Western Han Dynasty.
