History of the world
Whether in prehistoric or historic times, people always needed to be near reliable sources of potable water. Settlements developed on river banks as early as 3000 BCE in Mesopotamia, on the banks of Egypt's Nile River, in the Indus River valley, and along China's rivers. As farming developed, grain agriculture became more sophisticated and prompted a division of labour to store food between growing seasons. Labour divisions led to the rise of a leisured upper class and the development of cities, which provided the foundation for civilization. The growing complexity of human societies necessitated systems of accounting and writing.
Mu (lost continent)
There is evidence that the civilizations of the Americas and the Old World developed independently of each other and, in fact, agriculture and urban societies probably first developed after the end of the Ice Age, somewhere in the Levant some 10,000 years ago and gradually spread outwards from there to the rest of the Old World. The development of the oldest known cities, such as Çatalhöyük, can more easily be attributed to local and gradual evolution than to the coming of refugees from a "superior civilization".