The Mekong Delta region of Vietnam displays a variety of physical landscapes, ranging from mountains and highlands to the north and west to broad, flat flood plains in the south. This diversity of terrain was largely the product of tectonic uplift and folding brought about by the collision of the Indian and Eurasian tectonic plates about 50 million years ago. The soil of the lower Delta consists mainly of sediment from the Mekong and its tributaries, deposited over millions of years as the river changed its course due to the flatness of the low-lying terrain.