History of the world (or "World History") is generally taken to encompass the history of the human race (Homo sapiens), from the earliest times to the present, in all places on earth. By convention, it generally excludes non-human natural history and geological history, except insofar as the natural world substantially affects human lives. It encompasses the study of written records, from ancient times forward, plus additional knowledge gained from other sources, such as archaeology. Ancient recorded history[1] begins with the invention, independently at several sites on Earth, of writing, which created the infrastructure for lasting, accurately transmitted memories and thus for the diffusion and growth of knowledge.[2][3] However, the roots of civilization reach back to the period before writing — humanity's prehistory.
Human prehistory begins in the Paleolithic, or Early Stone Age. During the Neolithic (New Stone Age) Agricultural Revolution between 8,500 and 7,000 BCE in the Fertile Crescent, humans began the systematic husbandry of plants and animals — agriculture.[4][5][6] It spread to neighboring regions, and also developed independently elsewhere, until most humans lived as farmers in permanent settlements.[7] The relative security and increased productivity provided by farming allowed these communities to expand. They grew over time into increasingly larger units in parallel with the evolution of ever more efficient means of transport.
Surplus food made possible an increasing division of labor, the rise of a leisured upper class, and the development of cities and thus of civilization. The growing complexity of human societies necessitated systems of accounting, which led to writing.[8]
Civilizations developed on the banks of life-sustaining bodies of fresh water (lakes and rivers). By 3,000 BCE they had arisen in the Middle East's Mesopotamia (the "land between the Rivers" Euphrates and Tigris),[9] on the banks of Egypt's River Nile,[10][11][12]...