Landed property, indeed, did not contribute at all to that awakening of commercial activity which, after the disasters of the Norman invasion in the North and the Saracen raids on the shores of the Mediterranean, began to manifest itself toward the end of the tenth century and the beginning of the eleventh. Its preliminary manifestations are found at the two extremities of the Continent, Italy and the Low Countries. The interior seas, between which Europe was restricted in her advance toward the Atlantic, were its first centres of activity. Venice, then Genoa and Pisa, venture on the coasting trade along their shores, and then maintain, with their rich neighbors of Byzantium or of the Mohammedan countries, a traffic which henceforward constantly increases. Meanwhile Bruges at the head of the estuary of the Zwyn, becomes the centre of a navigation radiating toward England, the shores of North Germany, and the Scandinavian regions. Thus, economic life, as in the beginning of Hellenic times, first becomes active along the coasts. But soon it penetrates into the interior of the country. Step by step it wins its way along the rivers and the natural routes. On this side and on that, it arouses the hinterland into which the harbors cut their indentations. In this process of growth the two movements finally meet, and bring into communication the people of the North and the people of the South. By the beginning of the twelfth century it is an accomplished fact. In 1127 Lombard merchants, journeying by the long route which descends from the passes of the Alps toward Champagne and the Low Countries, reach the fairs of Flanders.