A state is a polity under a system of governance with a monopoly on force. There is no undisputed definition of a state. A widely used definition from the German sociologist Max Weber is that a "state" is a polity that maintains a monopoly on the legitimate use of violence, although other definitions are not uncommon. A state is not synonymous with a government, as stateless governments like the Iroquois Confederacy exist. Some states are sovereign (known as sovereign states), while others are subject to external sovereignty or hegemony, wherein supreme authority lies in another state.