Southern (other name: Nam Ky) is the southern region of Vietnam after Vietnam gained its independence in 1945. Southern is one of three main areas of Vietnam's territory includes Northern, Central and Southern. The researchers said that the history of this land millions of years ago is a big gulf but has been accredited by the Mekong river sediment. The two largest river systems of Southern is Mekong river and Dong Nai river. So far, regional Mekong Delta is a land still low, average height above sea level is only about 5 meters. Some areas, such as the Long Xuyen quadrangle, Dong Thap Muoi and west of Hau Giang river exist below sea level, that is why every year to 1 million hectares flooded salt in the period from 2 to 4 months.