Occupying a long, thin part of the Indochinese peninsula, Vietnam shares borders with China, Laos and Cambodia. Much of Vietnam’s terrain is mountainous, particularly the north and central highland regions. Although people still choose to live in the densely forested highland regions, most of Vietnam’s population is concentrated in the cities of the low lying areas, where infrastructure is more easily built and the land is fertile. One of the 12 great rivers of the world, the Mekong, runs through Vietnam and has been responsible for wide-scale flooding. A system of canals and levees has been quite successful in redistributing the water during monsoons, and has helped to alleviate flooding in the Mekong Delta and surrounding areas.