To collect and classify the function words in palm-leaf documents that developed from body-part and plant-part nouns in Lanna Thai. The factors and processes that motivate body-part and plant-part nouns to develop into classifiers, relative markers..., pronouns and prepositions are also studied. Body-part and plant-part nouns develop into 4 types of function words: classifiets, relative markers, pronouns and prepositions. As for the body-part nouns, 10 develop into classifiers, 3 into relative markers, 4