Westphalia is roughly the region between the rivers Rhine and Weser, north and south of the Ruhr River. During the course of history, different places and regions were called "Westphalia", the borders of the region can therefore not be defined exactly, as they depend on the entity and time talked about. For the same reason, there are different specifications of its area and number of people. They range between in land area, and between 4.3 million and 8 million people. There is a consensus that Münster, Bielefeld and Dortmund are part of Westphalia.