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.
Cradle of civilization
The earliest evidence of agriculture in the Andean region dates to around 4700 BC at Huaca Prieta and Paredones. The oldest evidence of canal irrigation in South America dates to 4700 to 2500 BC in the Zaña Valley of northern Peru. The earliest urban settlements of the Andes, as well as North and South America, are dated to 3500 BC at Huaricanga, in the Fortaleza area, and Sechin Bajo near the Sechin River.