Dongba (also Tomba; the Naxi call it “wood records” or “stone records”) is a pictographic script used by the dto¹mba, the priests of the Naxi religion, to record ritual texts. It is largely a mnemonic system: a glyph prompts a recitation rather than spelling out words, so the same glyph can carry different readings, and a scribe may add geba syllabary signs to fix the reading. UNESCO's nomination of the Ancient Naxi Dongba Literature Manuscripts for the Memory of the World register describes the script as having more than two thousand characters.
Dongba is pictographic and not phonetic in the way an alphabet is. Many glyphs are recognisable pictures — a person, an animal, an action — and abstract words are often written by rebus: a glyph for a similar-sounding concrete word stands in. Because of that, Dongba cannot by itself render the Naxi language unambiguously, and different scribes used the same glyphs for different things. It is best described as an aid to an expert reciting a text he already knows.
It was the working script of the Dongba priests, for scriptures, ritual manuals and divination. It was not a script for letters, accounts or daily life. This is one reason the material is fragile in a specific way: the texts survive on handmade paper in priestly hands, and when the tradition of reading them thins, the script stops being readable even where the pages still exist. UNESCO's nomination states the problem directly — that only a few masters able still to read the scriptures remain, and that the literature is "on the brink of disappearing".
The Ancient Naxi Dongba Literature Manuscripts are inscribed on UNESCO's Memory of the World register.
Geba is a syllabary that was sometimes written alongside Dongba glyphs to disambiguate a reading. It is a separate system with a different history; treat "Dongba script" and "geba" as two things, not one.
NaxiAI. “What is the Dongba script?” https://naxiai.com/dongba-script.