Frederic was in fact dismantling the feudal system of government inherited from the Normans, his "magna curia" and minor dignitaries were usually chosen from lay orders (like his poet-notaries). He also abolished internal barriers: free trade brought prosperity to the South, making Bari (as witnessed by Cielo in his "Contrasto") one of the richest cities in the Mediterranean. But, keeping this modern state afloat, meant that his barons had no power to collect taxes, their greatest source of revenues. Hence the necessity for Frederick to bring law and order by moving his court to and fro.