How did Chinese characters become part of writing systems for Central and Northern Tai dialects?

The writing system used by the Central and Northern Tai dialects is derived from Chinese characters. While the exact origins of its adoption remain uncertain, this system has been employed primarily for writing songs and may have been in use for a significant period, with some characters undergoing modifications since the 18th century.1

This Chinese-based script is distinct from the writing systems used by the Southwestern group of Tai languages, which are derived from Indic sources. The integration of Chinese characters into these specific Tai dialects reflects a long history of linguistic contact, as evidenced by the abundance of Chinese loanwords found in the Central and Northern dialects. Unlike the Southwestern scripts, which evolved from the Southern Indic type of script, the Central and Northern Tai dialects adopted the logographic principles of the Chinese writing system to suit their own linguistic needs.123