After the spread of the Manichaean religion in Khorasan and Transoxiana with the efforts of Manichaean missionaries, the Parthian language was used as a tool for promoting the Manichaean religion and hence books were written or translated in this language. Some of these books have been found in northwestern China. The handwriting used for these texts is the same as the Manichaean handwriting said to be invented based on Tadmori handwriting by Mani himself. The Manichaean handwriting goes from right to left and its main characteristic is lack of Hezvarash which makes this writing very easy to read. Also unlike the Parthian writing in which each letter can have different phonetic values, in Manichaean handwriting each letter can only have one phonetic value. Parthian texts written in Manichaean handwriting are:

1. Works of Mani and his students: these writings were compiled when the Parthian language was still used (in 3rd or the 4th century AD). The most important work is parts of "Ardahand Vafras" which analyzes Mani's main book, "Arjang".
2. Mani's recent work: which are usually about the Dinavarieh sect.

It was mentioned that by this time, Parthi was a dead language and that is why in many cases the influence of Middle Persian words and grammar is evident. Manichaean texts written in Parthi language include subjects such as: principles of faith, songs praising God and religious leaders, letters of advice, personal letters, charms, prayers, stories and proverbs. A considerable part of these texts are poems.