A gradual economic shift occurred during the Muradid era, as corsair raiding decreased due to pressure from Europe, and commercial trading based on agricultural products (chiefly grains) increased due to an integration of the rural population into regional networks. Mediterranean trade, however, continued to be carried by European shipping concerns. The Beys, in order to derive the maximum advantage from the export trade, in addition to taxation instituted government monopolies which mediated between the local producers and foreign merchants. As a result, the rulers and their business partners (drawn from foreign-dominated elites connected to the Ottomans) took a disproportionate share of Tunisia's trading profits. This precluded the development of local interests, whether rural landowners or a wealthy merchant strata. A social divide persisted, with the important families in Tunisia identified as a "Turkish" ruling caste.