The Dvaravati period lasted from the 6th to the 13th centuries. Dvaravati refers to both a culture and a disparate conglomerate of principalities. By the 10th century, Dvaravati began to come under the influence of the Khmer Empire and central Thailand was ultimately invaded by the Khmer king Suryavarman II in the first half of the 12th century. Haripunchai survived its southern progenitors until the late 13th century AD. when it was incorporated in the Lanna Kingdom. The people of the region used the ancient Mon language, but whether they were ethnically Mon is unknown. There is evidence that these principalities may comprise many cultural groups of people, including Malays and Khmers. The theory of Thai migration into Dvaravati has been refuted and is now known to have happened much later. The term Dvaravati derives from coins which were inscribed in Sanskrit with sri dvaravati. The Sanskrit word dvaravati means 'with many gates'. Its name may derive from the mythical city of Dvaraka