During Rama II era, the king was very pleased with Sunthorn Phu. The king was so pleased with Sunthorn Phu, in fact, that he was promoted to be Khun Sunthorn Voharn. In King Rama III monanchy, Sunthorn Phu made one detrimental mistake by correcting the king's poem in the presence of the king and King's officers. Sunthorn Phu was stripped of his farmer title as punishment. He entered the Buddhist priesthood but eventually left the priesthood to become a merchant. King Rama IV's princess read his poems called “Phra Apai Manee ". She was very pleased and she asked him to finish the poem. The King Rama IV promoted him to Phra Sunthorn Voharn. He spent the rest of life at peace until he died in 1855. He left behind a legacy of poems that have become famous over time because they describe Thai history. Thai people now study his poems to learn about the history of their country. His poetic works were honored by UNESCO.