The main economic activity throughout the Jewish Middle Ages was local and regional. Jewish mercantile activities were regulated by halakha and by the laws of their ambient societies, as well as by an interplay of the two, and many contemporary scholars postulate that Christian or Islamic economic law superseded Jewish law in most areas. In Ashkenaz, these local and mostly small-scale transactions were regulated by the herem ha-yishuv (settlement clause), a measure resembling excommunication that gave communities the right to veto the settlement of newcomers, and by maarufiya (regular clientele), a principle that regulated access to regular customers.