Thus a darkening or eclipse of intellectual life took place to a vast extent when the western Roman Empire succumbed to the barbarians of the North, and the bands which for centuries had united the cities of the east and west were violently sundered. Under that fatal blight Civilisation vanished from the lands which had so long been her chosen seat, only to dawn again after a long and obscure night. Commercial intercourse ceased between the sea-ports of the Mediterranean, all communication with distant countries was cut off, and the boundaries of the known earth became more and more narrow, as the ignorance of a barbarous age increased.
It is not before the beginning of the ninth century that we perceive the first glimpses of a better day in the rising fortunes of some Italian sea-ports, where favourable circumstances had given birth to liberal institutions. As early as the year 840 Amalfi possessed a considerable number of trading-vessels, and carried on a lucrative commerce with the Levant. The maritime code of this little republic regulated the commercial transactions of all the Mediterranean sea-ports; as in a later century the law-book of Wisby served as a guide to the merchants of the Baltic. A few years after its submission in 1131 to the arms of King Roger of Sicily, Amalfi was plundered by the Pisanese and almost entirely destroyed. The neglected harbour was gradually choked with sand, and the little town, which now numbers no more than 3000 inhabitants, has nothing to console it for its actual poverty but the remembrance of a glorious past. Along with Amalfi, Gaëta, Naples, and Pisa, rose to considerable eminence in commerce, though far from equalling the power and splendour of Genoa and Venice, the great republics of northern Italy.
As far back as the beginning of the sixth century, the city of the lagunes fits out a small fleet to purge the Adriatic of Istrian pirates. By a prudent course of policy she renders herself indispensable to the Byzantine court, and acquires great privileges in Constantinople. It is here she purchases the costly productions of the East, with which during the ninth and tenth centuries, she provides Northern Italy and a great part of Germany. About the beginning of the eleventh century her trade with Egypt and Syria begins to flourish, and soon raises her to the pinnacle of her power and wealth. In the year 1080 she extends her rule over Croatia and Dalmatia, and gains in 1204 considerable advantages by assisting the western crusaders in the conquest of Constantinople. Pera, numerous coast towns from the Hellespont to the Ionian Sea, a great part of the Morea, Corfu, and Candia fall to the winged lion's share, and requite the services of "blind old Dandolo." The silk manufacture is transported, as a valuable fruit of conquest, from the Morea to Venice, and becomes a new source of wealth to the Adriatic Tyre. The Euxine opens her ports to the Venetian seamen, treaties of commerce are concluded with Trebizond and Armenia, and a factory is established at Tana, at the mouth of the Don.
While thus the power of Venice rises more and more in the East, Genoa, which already in the tenth century carried on a flourishing trade, acquires by degrees the supremacy in the Western Mediterranean. The aid afforded by the republic to the Greek emperor Michael Palæologus contributes largely to the overthrow of the Latin throne of Constantinople, and opens the Bosphorus and the Black Sea to the enterprise of her merchants. The grandeur of Genoa now reaches its height; she holds fortified possession of Pera and Galata, and covers the coasts of the Crimea with her strong-holds and castles.
At a later period the Florentines appear on the scene, and assume the rank formerly held by Pisa in Mediterranean commerce. The acquisition of the sea-port of Leghorn (1421) opens the barriers of the ocean to the birthplace of Dante and Galileo.
After their deliverance from the Moorish yoke in the ninth century, a fresh and vigorous spirit begins also to animate the Catalans. They conclude treaties of commerce with Genoa and Pisa, and towards the end of the thirteenth century the ships of Barcelona are found visiting all the ports of the Mediterranean.
But in spite of the growth of trade and navigation in Italy and Spain, many years had yet to elapse after the fall of the Roman empire ere the gates of the Atlantic were once more opened to the navigators of the Mediterranean. It was not before the middle of the thirteenth century, after Seville and a great part of the Andalusian coast had been wrested from the Moors by Ferdinand of Castile, that the Italian and Catalonian seafarers, encouraged by privileges and remissions of duties, began to visit the port of Cadiz, where they met with merchants from Portugal and Biscay. Soon after, and most probably in consequence of the connexions thus formed, we find Italian ships visiting the ports of England and the Netherlands. About 1316, Genoese vessels began to carry goods to England; and somewhat later the Venetians, whose visits are not mentioned by the chroniclers before 1323.
Thus after a long interruption we see the seamen of the Mediterranean at length resuming the track to the Atlantic ports that had been struck out more than thirty centuries before by their predecessors the Phœnicians. But their voyages to the western ocean took place under circumstances much more favourable than those which had attended the men of Tyre and Carthage in their adventurous expeditions. Not only the better construction of their ships, but still more the use of the mariner's compass, for which Europe is probably indebted to the Arabs, who in their turn owed its knowledge to the Chinese, enabled them to steer more boldly into the open sea, and regardless of the bendings of the coasts to reach their journey's end by a less circuitous route. The period when the magnetic needle was first made use of by the Mediterranean navigators is not exactly known, but so much is certain that it did good service long before the time of Flavio Gioja (1302), to whom its discovery has been erroneously ascribed, though he may have introduced some improvement in the arrangement of the compass. Humboldt tells us in his "Cosmos," that in the satirical poem of Guyot de Provens, "La Bible" (1190), and in the description of Palestine by Jaques de Vitry, bishop of Ptolemais (1204-1215), the sea-compass is mentioned as a well-known instrument. Dante also speaks of the needle which points to the stars (Paradise, xii. 29); and in a nautical work by Raimundus Lullus of Majorca, written in the year 1286, we find another proof of a much earlier knowledge of the compass than before the beginning of the fourteenth century, since its use by the mariners of his time is expressly mentioned by that author.
Confidently following this unerring guide, the Catalonians sailed at an early period to the north coast of Scotland, and even preceded the Portuguese in their discoveries on the west coast of Africa, since Don Jayme Ferrer penetrated to the mouth of the Rio de Ouro as early as August 1346. About the same time the long-forgotten Canary Islands were rediscovered by the Spaniards; and at a later period (1402-1405) conquered and depopulated by some Norman adventurers, the Bethencourts.