In 1637, when Sourigna Vongsa ascended the throne, Lan Xang further expanded its frontiers. His reign is often regarded as Laos's golden age. When he died without an heir, the kingdom split into three principalities. Between 1763 and 1769, Burmese armies overran northern Laos and annexed Luang Prabang, while Champasak eventually came under Siamese suzerainty.