Evidence that trade remained active, if not exactly busy, does exist. In 716 the Frankish king of Gaul, Chilperic II, granted to the monks of Corbie handsome tax exemptions and permitted them to import papyrus and other eastern goods through Fos-sur-Mer in the Rhône delta, though he was merely confirming older privileges, so this does not prove that business through Fos was still lively.9 In its heyday Fos channelled northwards not just Spanish leather and papyrus (fifty quires each year) but 10,000 pounds of oil, 30 drums of stinking fish-sauce, 30 pounds of pepper, five times as much cumin, as well as massive amounts of figs, almonds and olives, assuming these quantities ever actually arrived. As has been seen, Marseilles, nearby, was one of the few ports in the north-western Mediterranean that had not withered completely. Archaeological investigations show that the city actually grew during the sixth century and that the ties to Carthage and its region remained strong after 600. There was even a local gold coinage, testifying to Mediterranean links, since there was no reliable source of gold within western Europe. But by the end of the seventh century Marseilles was under pressure. The loss of Carthage to the Arabs meant that its ties to Africa were sundered. The supply of gold dried up and the coins could not be minted, while eastern amphorae no longer arrived.
One group of adventurous, multilingual Jewish merchants known as the Radhaniyyah, or ‘Radhanites’, was described by the ninth-century Arab writer ibn Khurdadbih. He listed four routes along which these merchants travelled, some overland through Gaul and past Prague to the kingdom of the White Bulgars that stretched over vast open spaces north of the Black Sea, others by sea from Provence to Egypt and then down the Red Sea to India, or from Antioch in the Levant to Iraq, India, Ceylon and by sea once again to the Far East. Some, however, set out from Spain and made their way to the Levant by following the North African coast, a route easier to follow by land than by sea, because of shoals and contrary winds and currents. Radhanite merchants returning from the Nile Delta might take ship for Constantinople, or they might find a route back to Gaul. These descriptions of their routes cast the Radhanites in the role of spice merchants, carrying condiments, perfumes and drugs, though their northern contacts enabled them to bring iron weapons, furs and slaves down to the Mediterranean, where Muslim buyers were short of iron and glad to purchase swords from the north. Alongside the Radhanites there were many other slave traders, Christian and Muslim; by 961 there were 13,750 Saqaliba, Slav slaves, living in Muslim Córdoba. Warfare between Germanic and Slav peoples in the Wendish lands in what is now eastern Germany ensured a plentiful and regular supply of captives, and the terms sclavus and ‘slave’ recall the Slavonic origin of very many of these slaves. Slaves from the Slav borderlands arrived in Syria and Egypt as well, along with Circassians brought down from the Black Sea. Though horrible, the fate of these slaves, even those who survived the trauma of castration, was not always comparable to the fate of the slaves carried in such vast numbers across the Atlantic towards the Americas in later centuries. Strong-looking young men were not emasculated but entered the emir’s guard in Córdoba, sometimes rising to a high military command. On the other hand, women might enter the closed world of the harem; and handsome boys fell into the possession of pederast princes. One merchant who fits the Radhanite label well was Abraham of Saragossa, a Spanish Jew who benefited from the personal protection of the Frankish emperor Louis the Pious. He was active around 828 and was exempt from the payment of tolls; he was explicitly permitted to buy foreign slaves and to sell them within the Frankish lands, but in 846 Jewish merchants were accused by the archbishop of Lyons of looking no further than the cities of Provence for their source of supply, and of selling Christian slaves to buyers in Córdoba.
Whereas Roman naval power had been based on the extinction of piracy, Muslim naval power was based on the exercise of piracy. It was this that made service in Muslim fleets palatable to the Greeks, Copts, Berbers and Spaniards who undoubtedly manned the ships. Western shipping was freely targeted by pirates in the service of Muslim rulers. A ninth-century Arab writer described how Christian ships in the Mediterranean could be treated as a legitimate target for Muslim pirates when the ships were heading for other Christian lands; if a ship was seized and its captain insisted that he was travelling under the protection of a Muslim ruler such as an Andalucían emir, written proof could be demanded. Although the invasion of Spain by Arab and Berber armies in 711 had involved few naval operations – apart from the crucial one of crossing the Straits of Gibraltar – the rest of the eighth century saw Muslim fleets gain in confidence in the western Mediterranean. An outburst of piracy after the fall of Carthage in 698 was suppressed easily enough by the Byzantine navy, but the Byzantine loss of effective control of the seas west of Sicily allowed Muslim fleets a free hand off the islands and coastlines that still acknowledged, even if remotely, Byzantine overlordship: the Balearic islands, Sardinia, the Ligurian coast.
The safety of this region deteriorated seriously around 800. Naval skirmishes erupted all over the surface of the western Mediterranean. These events are generally presented as a struggle to hold back Arab invaders who were trying to gain mastery of the Mediterranean islands. Often, though, the Muslim navies were more intent on grabbing booty (including captives, whom they would put on sale), than in trying to extend the dominion of Islam. The Christians too were keen to take slaves and to win booty, even though they were more obviously on the defensive. Moreover, precisely because there was now a great power in the west willing to fight back against the Muslim navies, tension increased and the pirates became ever more daring. In 798 Arab navies attacked the Balearic islands, which had not been a target of the original invasion of Spain. Knowing that Constantinople was incapable of offering any help, the islanders turned instead to the ruler of Gaul and northern Italy, Charlemagne, whom they acknowledged as their new overlord. Charlemagne sent some forces and the Arabs were repelled the next time they raided the islands. He ordered his son Louis to build a fleet for the defence of the Rhône delta, and he commissioned new coastal defences to protect the ports of southern France and north-western Italy. Hadumar, the Frankish count of Genoa, led a fleet against Arabs invading Corsica, and was killed in the fray. Fighting continued off both Corsica and Sardinia, and a Frankish admiral named Burchard destroyed thirteen enemy ships. Meanwhile, the Venetians (of whom more shortly) patrolled the waters off Sicily and North Africa and they or other ships in Byzantine service scored notable victories against ships from al-Andalus, Islamic Spain. Thirteen Arab ships that attacked the small but strategically valuable island of Lampedusa, between Sicily and Africa, were wiped out by the Byzantines in 812. Before long the North Africans decided that events had gone far enough, and they arranged a ten-year truce with Gregorios, the governor of Byzantine Sicily. Christian navies were now in command west of Sicily, while the Byzantines had gained a much needed respite in the central Mediterranean – the Arab raids on Sicily and Calabria had caused great damage to the exposed coastal towns and villages.
Unfortunately for the Byzantines, the Muslims decided that they wanted more from Sicily than slaves and booty, launching an invasion in 827 which slowly brought the entire island under the rule of the Aghlabid emirs of North Africa. They renewed their raids on Sardinia and Corsica, to which the Franks responded with an ambitious naval attack on the African coast. The problem was that the Frankish navy had no permanent base, and, even after winning a succession of engagements, a single defeat at Sousse was enough to force the Franks out of Africa. In any case, the Frankish empire had passed its peak with the death of Charlemagne in 814, and his successor Louis the Pious was distracted from the western Mediterranean by internal rivalries. In the 840s, the Arabs were free to raid Marseilles, Arles and Rome. To the extreme embarrassment of both the Byzantines and the Franks, who each claimed dominion over southern Italy, a Muslim navy captured the seaport of Bari in 847, establishing an emirate that lasted until 871, when finally the Franks and the Byzantines learned to work together long enough to expel the Muslims. After tentative moves in the ninth century, Arab pirate bases were established in the tenth century along the coast of Provence, and a little way inland at Fraxinetum (La Garde-Freinet). Arab piracy gravely endangered Christian trade out of Provence, while providing the Muslims with a supply of slaves and war booty.