In the east the Annamite Range formed a barrier, but the areas of Muang Phuan and Xam Neua were regular points of commerce with Vietnam. Trade from Thakhek and Champasak flowed down the Mekong to the Island of Khong, where the goods would then be portaged past Si Phan Don and the Khone Falls to join with the Mekong again and on to the Khmer in the south. Lao merchants ("lam") would travel to Lao Theung and Lao Sung areas to exchange cloth, iron and silver for forest products, which would be floated via streams on bamboo rafts until they met with larger rivers.