According to Wikipedia, “The Dongba, Tomba or Tompa or Mo-so symbols are a system of pictographic glyphs used by the ²dto¹mba (Bon priests) of the Naxi people in southern China. In the Naxi language it is called ²ss ³dgyu 'wood records' or ²lv ³dgyu 'stone records'. "They were developed in approximately the seventh century." (World Digital library) The glyphs may be used as rebuses for abstract words which do not have glyphs. Dongba is largely a mnemonic system, and cannot by itself represent the Naxi language; different authors may use the same glyphs with different meanings, and it may be supplemented with the geba syllabary for clarification.”
In preparation as of 2021: un cours en ligne sur l'écriture Dongba (an English version will follow)