j1=b1 is a Sinitic language used by b2 to communicate b3 (si'o/du'u).
Refers to all languages in the Sino-Bai branch of Sino-Tibetan, including Old and Middle Chinese and possibly the Bai langauges. Not synonymous with "Mandarin" (use ca'irjugbau instead). See also jungo, bangu, jugygu'e, djunguos, xa'anzu.