Not starting an argument, but no Thai is pure. They have either Lao (Northern Thailand) Malay (Southern Thailand), Khmer (southeast Thailand) or Chinese (Central/ Bangkok) mixed with Tai/ Kadai (Northern Viet Nam and Southern China)) admixture. And if she's from Buri Ram, she most likely has Khmer blood too.
My Thai wife is Thai from her mother side and Lao and Chinese from her father side.