History of the Thai Forest Tradition
The Kammatthana meditation tradition originally grew out of the Dhammayut reform movement, founded by Mongkut in the 1820s as an attempt to raise the bar for what was perceived as the "lax" Buddhist practice of the regional Buddhist traditions at the time. Mongkut's reforms were originally focused on scriptural study of the earliest extant Buddhist texts, revival of the dhutanga ascetic practices, and close adherence to the Buddhist Monastic Code (Pali: vinaya).
Source: Wikipedia — History of the Thai Forest Tradition (CC BY-SA 4.0)