The hPhags-pa script was created under the order of Khubilai, the Great Khan of the Mongols, as an official and universal script for his vast empire that stretched from China to Russia and crossed ethnic and cultural borders. The script already employed to write Mongolian at that time was originally borrowed from the script used to write Uighur, a Turkic language, and did not fit well phonetically with Mongolian. Therefore, in 1269 CE, the Khan charged his personal lama, Matidhvaja Sribhadra, also known as hPhags-pa Lama, to create a script to replace the existing Mongolian script. Since hPhags-pa Lama was Tibetan, he created a new script based on his native Tibetan script, but he also borrowed some elements from Mongolian as well.
Visually, the letters of the hPhags-pa script appear very rectangular, hence the origin of one of its names, dörbeljin üsüg, meaning "square script" in Mongolian. However, a comparison with Tibetan reveals that the letters are essentially more angular versions of Tibetan scripts.
Like Tibetan, the hPhags-pa script is a syllabic alphabet. The basic hPhags-pa letter represents a consonant plus the vowel /a/. The only exception is the letter used to write the first syllable in vowel-initial words, as it does not have an initial consonant and only denotes only the single sound /a/. The following chart illustrates the basic letters in the hPhags-pa script.
To write a syllable with a vowel other than /a/, an extra sign is written after the basic sign. The following are the vowel markers.
However, as the vowel markers were directly borrowed from Tibetan, they lacked two sounds found in Mongolian, namely /ö/ and /ü/. To represent these sounds, two vowel markers are used. The sound /ö/ is written as eo, and /ü/ is written as eu.
Another characteristic borrowed from the Mongolian script is that the hPhags-pa script is written in vertical columns, which are read from left to right.
While originally designed to replace the Mongolian script, Khubilai Khan decided to make it into the universal script of the Mongol Empire. However, even though it became the official script of the Mongolian Empire and therefore all state business and affairs were written in this script, few adopted it as an everyday script outside the bureaucracy. A few examples of the hPhags-pa used to write Mongolian, Chinese, Sanskrit, and Tibetan have been found, but for the most part people continued to use the script they knew best. As the Mongolian Empire fractured, so did the hPhags-pa script cease to be used. From conception to demise, the hPhags-pa script lasted no more than 100 years.