This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Mongolian Letters gathers the thirty five signs of the traditional Hudum alphabet, written in vertical columns running down the page and read left to right across them, the only script in current national use that runs this way.
Adapted from the Old Uyghur alphabet around 1204, itself descended through Sogdian from Aramaic, the script is economical to the point of real ambiguity: O and U share one written shape entirely, as do the front rounded pair Oe and Ue, and a reader tells them apart only from the word, not the sign. Mongolian vowel harmony sorts its vowels into a back class and a front class, with I standing neutral to both, and that harmony governs which of several paired consonant shapes, such as Qa and Ga, a word takes; the two are distinguished, where a writer bothers, by dots that ordinary handwriting often omits.
Native Mongolian words never begin with P, so any word opening on Pa is a loanword, overwhelmingly from Tibetan, Sanskrit or Chinese Buddhist vocabulary, which the script has carried since the sixteenth and seventeenth century translation of the Kangyur into Mongolian. The alphabet remains the official script of Inner Mongolia and has been revived alongside Cyrillic in the state of Mongolia, distinct from the related Todo, Sibe and Manchu writing systems that were built on the same letters for other languages.