Li Thai served as Upparat (viceroy) during his father's reign from the city of Si Satchanalai, an important urban center of the early Sukhothai Kingdom.

According to George Cœdès, Li Thai's devotion to Buddhism and his religious works earned him the title Maha Thammaracha, meaning "great pious king".

[3] As Li Thai admired Buddhism greatly, he used Buddhism as a diplomatic, educational, and governing tool, having also wrote the religious text Traiphum Phra Ruang during his time as a Upparat (viceroy), which has been used in teaching the citizens to do good and to abstain from doing evil, this book is then continued to be an important text that is used in Thailand's education up to the present date.

[5] Lithai has spread the teaching of Buddhism through many methods, primarily in the form of Traiphum Phra Ruang text, but also through the construction of temples and famously in becoming a priest himself during the year 1362, serving as an example for the citizens to follow.

He has also invited a Buddhist Patriarch from Lanka to enrich Buddhism in Sukhothai, having also repair many temples and build many Buddha statues such as Prahphuddachinnasri.

[6] Lithai having dedicated himself in the enrichment of Buddhism all his life, has been given the title of a Thammaracha, meaning a king who grants satisfaction through Dharma.

[10] Because Traiphum Phra Ruang is a Buddhist text, it has been written with many uncommon words that originated from Pali/Sanskrit language, serving as a prime case study of literature and literacy during Sukhothai era.

In modern times, Traiphum Phra Ruang still serves as an academic book for religion and literature classes in Thailand due to its elegant usage of language.