Rivers begin where there is abundant rainfall but then flows for hundreds of miles into and through arid regions. Rivers can create ribbon oases which sustain life for plants and animals that otherwise could not be in the more arid region. Riverine oasis serve as flyways for birds and migration routes for animals moving from one ecosystem to another. There are animals that other wise would neither be present in more arid regions nor be so concentrated making them highly accessible to humans. Water Influences Human Society.
Water can be both a source of social integration and for society separation.
Rivers are a source of travel for humans, thus permitting frequent and rapid communication and the formation of more complex and widespread social systems. Rivers can be a natural boundary between ethnic groups, thus places of either interethnic competition or cooperation. The control of water can become a organizing feature of society, especially when it is used in irrigated farming . Human population density was higher along water courses, thus settlements there tended to be the center of human life in the region. Other Forces' Response To Water Water Spirits.