Where did the world's first cities appear?

The emergence of the world's first cities primarily occurred in ancient Mesopotamia between 4000 and 3500 BC. This region, often referred to as the "Cradle of Civilization," was characterized by significant advancements in agriculture, trade, and social organization, which facilitated urban development. The fertile land between the Tigris and Euphrates rivers supported agricultural surplus, leading to population growth and the establishment of complex societies.

These early cities, such as Uruk, are notable for their significant architectural developments, including the construction of temples and city walls, as well as innovations like writing and advanced governance structures. The concentration of populations in these urban centers marked a pivotal shift in human social organization, distinguishing urban life from earlier, more nomadic or smaller-scale agrarian communities.

The other regions mentioned, while they have their own rich histories and later developments, did not establish cities as early as Mesopotamia. North America saw different forms of societal structures, ancient China developed significant cultures and cities later, and the Indus Valley civilization arose after the initial urbanization of Mesopotamia.