During the first centuries of the 2nd millennium BCE, Assyrian merchants originating from Assur, on the Upper Tigris, organized large scale commercial exchanges with central Anatolia. They settled in several localities, called kārums. This Akkadian word, which usually designates the quay or port in Mesopotamian cities, refers in Anatolia to the Assyrian merchant district and its administrative building. Thus, the kārum period— which comprises the Old Assyrian period—covers the time period during which the Assyrians traded in Anatolia, from the middle of the 20th to the end of the 18th century BCE; it corresponds, more or less, to the Middle Bronze Age. In Anatolia, this period is characterized by an important phase of urbanization, with a flourishing material culture mixing native and foreign styles.