There is no clear historical evidence of this Lord Buddha's head, but It is assumed that when Ayutthaya ( Former Thailand's capital for 417 years) was defeated by Burmese army in 1767, the Mahathat temple was set on fire and entirely destroyed and as its result most of the images and parts fell to the ground. The temple was deserted for more than a hundred years and many trees had grown at the spot covering the head or in 1957 when the Department of Fine Art undertook restoration might have gathered all the remains but could not complete. Second assumption is a thief might have tried to steal but due its weight could not carry it across the wall or someone had come to the scene and the thief left it there until the covered it as we see at present.