The Phagspa English pronunciation: /pʰɑgz.pɑ/, /pʰɑs.pɑ/[citation needed], ʼPhags-pa or ḥPʻags-pa script[1] is an alphabet designed by the Tibetan monk and State Preceptor (later Imperial Preceptor) Drogön Chögyal Phagpa (1235–1280) for Kublai Khan (r. 1264–1294), the founder of the Yuan dynasty (1271–1368) in China, as a unified script for the written languages within the Yuan.

[citation needed] Therefore, during the Yuan dynasty (c. 1269), Kublai Khan asked the Tibetan monk ʼPhags-pa to design a new alphabet for use by the whole empire.

ʼPhags-pa extended his native Tibetan alphabet[5] to encompass Mongol and Chinese, evidently Central Plains Mandarin.

[9] The resulting 38 letters have been known by several descriptive names, such as "square script", based on their shape, but today, are primarily known as the ʼPhags-pa alphabet.

Although it is an alphabet, ʼPhags-pa is written like a syllabary or abugida, with letters forming a single syllable glued or 'ligated' together.

Unlike Tibetan, in which vowels signs may not occur in isolation but must always be attached to a base consonant to form a valid syllable, in the ʼPhags-pa script initial vowels other than ꡝ a may occur without a base consonant when they are not the first element in a diphthong (e.g. ue) or a digraph (e.g. eeu and eeo).

Thus in Chinese ʼPhags-pa texts the syllables u 吾 wú, on 刓 wán and o 訛 é occur, and in Mongolian ʼPhags-pa texts the words ong qo chas "boats", u su nu (gen.) "water", e du -ee "now" and i hee -een "protection" occur.

An exception to this rule is the Mongolian word 'er di nis "jewels", where a single vowel sign is attached to a null base consonant.

Note that the letter ꡦ ee is never found in an initial position in any language written in the ʼPhags-pa script (for example, in Tao Zongyi's description of the Old Uighur script, he glosses all instances of Uighur 𐽰 e with the ʼPhags-pa letter ꡦ ee, except for when it is found in the initial position, when he glosses it with the ʼPhags-pa letter ꡠ e instead).

However, initial semi-vowels, diphthongs and digraphs must be attached to the null base consonant 'A (Letter 30).

In Chinese, and rarely Mongolian, another null base consonant ꡖ -a may be found before initial vowels (see "Letter 23" below).

[citation needed] The Shilin Guangji used Phagspa to annotate Chinese text, serving as a precursor to modern pinyin.