The history of Vietnam is one of the longest continuous histories in the world, with the oldest archaeological findings showing that people have been living there as far back as over a half million years ago. Ancient Vietnam was home to some of the world's earliest civilizations, with a cultural history of over 20,000 years - making them one of the world's first peoples who practiced agriculture. The Red River valley forms a natural geographic and economic unit, bounded to the north and west by mountains and jungles, to the east by the sea and to the south by the Red River Delta.