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.
State (polity)
Mesopotamia is generally considered to be the location of the earliest civilization or complex society, meaning that it contained cities, full-time division of labor, social concentration of wealth into capital, unequal distribution of wealth, ruling classes, community ties based on residency rather than kinship, long distance trade, monumental architecture, standardized forms of art and culture, writing, and mathematics and science. It was the world's first literate civilization, and formed the first sets of written laws.