Solidarity is the integration, and degree and type of integration, shown by a society or group with people and their neighbors. It refers to the ties in a society that bind people to one another. The term is generally employed in sociology and the other social sciences.

What forms the basis of solidarity varies between societies. In simple societies it may be mainly based around kinship and shared values. In more complex societies there are various theories as to what contributes to a sense of social solidarity.

`Asabiyyah refers to social solidarity with an emphasis on unity, group consciousness, and social cohesion, originally in a context of "tribalism" and "clanism", but sometimes used for modern nationalism as well. Ibn Khaldun's term is generally analogous to solidarity.

Ibn Khaldun argues, effectively, that each dynasty has within itself the seeds of its own downfall. He explains that ruling houses tend to emerge on the peripheries of great empires and use the unity presented by those areas to their advantage in order to bring about a change in leadership. As the new rulers establish themselves at the center of their empire, they become increasingly lax and more concerned with maintaining their lifestyles. Thus, a new dynasty can emerge at the periphery of their control and effect a change in leadership, beginning the cycle anew.