The demand for Lan Xang's high value trade commodities had to pass through intermediary kingdoms to reach world markets, thus for example when Japanese demand for forest products increased it was the Siamese which benefited from the trade. Maritime trade routes became more important than the Tea Routes in northern Lan Xang, the river trade along the Mekong and Chao Praya, or the overland trade with Vietnam. Trade with Europeans for weapons began as early as 1511 in Ayutthaya, and by contrast the first European trade mission to Lan Xang was not until the 1640s. Access to advanced European weapons proved decisive during the Burmese invasions of Lan Xang and would become more important in subsequent wars with Vietnam and Thailand during the eighteenth and nineteenth centuries.