This paper discusses the possibilities of applying the Text Encoding Initiative (TEI) guidelines to the encoding of a Mongolian historical record of the high middle ages, which has written in traditional Mongolian script. We have started to make mark-ups for named entities such as historical figures and place names, and erroneous ancient words, which were misspelled or written differently than orthography in ancient Mongolian historical documents. TEI encoded digital text representations that encodes the possible alterations, corrections, errors, commentaries, transcriptions, annotations and interpretations of an ancient Mongolian manuscript, along with the scanned images of the manuscript would help humanities scholars who are interested in using digital representations of Mongolian historical manuscripts as scholarly tools for digital humanities scholarship.