Ƅ (minuscule: ƅ) is a letter of the Latin alphabet used in the Zhuang alphabet and Bouyei alphabet from 1957 to 1986[1] to indicate the sixth tone, mid-level [˧]. The 'b' shape was chosen for the letter because it resembles the digit '6', and the character represents the sixth tone. In 1986, it was replaced by h.
↑Zhou, Minglang (2003). Multilingualism in China: The Politics of Writing Reforms for Minority Languages 1949–2002. Berlin: Mouton de Gruyter. pp.251–258. ISBN3-11-017896-6.