Asia
The coastal periphery was home to some of the world's earliest known civilizations, each of them developing around fertile river valleys. The civilizations in Mesopotamia, the Indus Valley and the Yellow River shared many similarities. These civilizations may well have exchanged technologies and ideas such as mathematics and the wheel. Other innovations, such as writing, seem to have been developed individually in each area. Cities, states and empires developed in these lowlands.
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".