Civilization is a cultural phenomenon that appears in human history. Its main features are complex institutions, a large population centered in cities and the development of a distinct cultural identity that unifies a group of communities. Civilization also includes a high degree of social specialization, technological advancement (although this progress was probably much slower in the pre-modern world), organized religion, and a broad range of arts. It has also led to the development of writing, standardized measurement, money, contract and tort-based legal systems, metallurgy, advanced mathematics, art, architecture, science, and philosophy.
Scholars have long debated what characteristics are necessary for civilization. They have argued whether the division of labor, centralized government, and a written language are essential elements. They have also debated whether social hierarchies are required for civilization to exist. Some historians have used the term to describe societies that are less developed than modern Western cultures, while others use it only for societies that they believe have achieved a high level of cultural sophistication.
Many civilizations evolved from agrarian communities that were able to supply enough food for people to live together in towns and cities. Cities centralized political, religious, and economic institutions that had previously existed in scattered smaller communities. This was a major step in the evolution of civilization. Eventually, some of these cities grew so large that they could sustain armies and other government services. This led to the formation of states. The states that emerged from these civilizations became the basis of modern nation-states.
The earliest civilizations formed in river valleys, usually near waterways that were useful for transporting grain and other crops. These early civilizations included Mesopotamia, which began around 4500 bce, ancient Egypt, which first formed in about 2500 bce, and the Indus Valley, which helped give rise to ancient India. Other factors that contributed to the formation of civilization include a surplus population, a need for a system of ruling, and a desire to share resources with other community members. In the case of the earliest civilizations, power was given and taken from above more or less simultaneously in a balanced transaction. In most cases, this was a form of coercive power.
Most scholars agree that civilization requires a system of government that can sustain a large and dense urban population. This system of government must be based on consensus and cooperation but also have the capacity to deal with disagreements or crises. It also must have the ability to regulate resource distribution and provide basic services. The emergence of this governmental structure, along with advances in farming and other technologies, allowed the creation of civilizations that could support a high level of cultural activity. These early civilizations also had a number of other cultural traits, including the decorative arts, musical arts, and literary arts that came about when spoken languages evolved. Civilization also seems to depend on a complex economic system, with trade and long-distance production allowing people to acquire a wide variety of other cultural goods and experiences.