Pirenne, Henri: The Expansion of Islam in the Mediterranean Basin 
Let no one imagine that the Musulmans of Africa and Spain, or even of Syria, could have taken the place of the former merchants of the Byzantine Levant. At first the Musulmans and the Christians were permanently at war. They had no notion of trading, but only of pillaging. The documents do not mention a single Musulman as established in Gaul or Italy. It is a proven fact that the Musulman traders did not instal themselves beyond the frontiers of Islam. If they did trade, they did so among themselves. We do not find a single indication, after the conquest, of any traffic between Africa and the Christians, with the already mentioned exception of the Christians of Southern Italy. But there is no sign of any traffic with the Christians of the Provencal coast.
Under these circumstances the only persons who were still engaged in commerce were the Jews. They were numerous everywhere. The Arabs neither drove them out nor massacred them, and the Christians had not changed their attitude to them. They therefore constituted the only class to make its living by trading. At the same time, thanks to the contacts which they maintained among themselves, they constituted the only economic link which survived between Islam and Christendom, or, one may say, between East and West.
41. Concerning the closing of the Occidental Mediterranean by Islam (but this does not refer to the Orient), see the text of the Christian Arab Yahya-Ibn-Said of Antioch, who, in the 11th century, stated that he had not a reliable list of the “patriarchs of Rome” since Pope Agathon (678-681). BEDIER, Charlemagne et la Palestine, REVUE HISTORIQUE, vol. CLVII, 1928, p. 281.
42. It is not by chance that the series of pseudo-Imperial coins in Gaul stops at Heraclius (610-641). Cf. PROU, Catalogue des monnaies mérovingiennes, pp. xxvii-xxviii.
43. According to KLEINCLAUSZ, La légcnde du protecrtorat de Charlemagne sur la Terre Sainte, SYRIA, 1926, pp. 211-233, Haroun granted the Emperor only the sepulchre of Christ. BEDIER, dealing with the same question, op. cit., REVUE HISTORIQUE, vol. CLVII, 1928, pp. 277-291, considers that although no protectorate was granted, Haroun did concede to Charles a “moral authority” over the Christians of Palestine.
44. R. BUCHNER, op. cit., p. 48, considers that there were still commercial relations at this date, but not later; more particularly because the Abbey of St. Denis did not again have its privileges confirmed. In 695 it obtained a villa in exchange for revenue in kind levied on the public treasury. PH. LAUER, Les diplomcs originaux des Mérovingiens, pl. 24. Cf. LEVILAIN, Etudes sur l’abbaye dc Saint-Denis, BIBL. ECOLE DES CHARTES. vol. XCI, 1930, pp. 288 et seq.
45. There was still a certain amount of navigation in the 8th century. For example, the Popes often sent their ambassadors to Pippin marino itinere on account of the Lombards. But the very fact that this is specially mentioned shows that it was exceptional. Similarly, the ambassadors sent by the Caliphs to Pippin and Charles came by way of Marseilles, Porto, Venice and Pisa.
46. BUCHNER, op. cit., p. 49, gives other examples, which show that there was no longer navigation between Marseilles and Rome. KLEINCLAUSZ is mistaken in declaring that the legates sent by Charlemagne to Byzantium embarked at Marseilles.
47. I admit that this does not hold good if the Cappil mentioned in 877 by the capitulary of Kiersy (M.G.H. CAPIT., vol. II, p. 361, §31) were, as is sup¬posed by M. THOMPSON, Economic and Social History of the Middle Ages, 1928, p. 269, Syrian merchants. But if we are to accept this we must assume with him that Cappi is merely the Latinized form of the Greek κάπηλος, which becomes Kapila in Syrian, meaning a merchant. But apart from the fact that this is a linguistic impossibility, it should be noted that the expression Cappi is applied only to the Jews. And lastly, this famous apax legomenon is undoubtedly due to a mistaken reading on the part of Sirmond, who, in 1623, edited this text from a manuscript which has since disappeared.