I just finished a 2001 book by that title, subtitled "Communications and Commerce, A.D. 300–900" by Michael McCormick (Cambridge University Press, 1101 pages). While awfully long, it's also very well written and a fascinating account of the origins of modern Europe.

The main theme of the book is the economic interchange between western Europe (especially the Carolingian Empire – Charlemagne and his descendants at the end of the period under consideration) and the east (the Byzantine Empire and the rising Islamic caliphate).

The two key chapters for me are chapter 24 (pp. 696-728) on the trade goods moving into Europe and chapter 25 (pp. 729-777) on the goods sold to the East to pay for those trade goods.

Coming west into Europe were gold and silver coins (both found in large quantities in archeological sites in Europe) and the silk, spices, and holy relics that many of us are familiar with from history classes in high school and college. What did the Europeans have to offer that was valuable enough to pay for these?

Of the 48 pages on European exports, THREE PAGES are devoted to lumber, furs, and Frankish swords. The remainder of the chapter is devoted to the trade in Europeans. Slaves were the main export item from Europe for that 600 year period (and later, though that's a different subject than this book).

By the end of the period, slaves were being preferentially sent to the Islamic world, where prices were higher than they were in the Byzantine Empire. There was regular commerce between Venice and Bagdad with slaves moving east and gold and spices moving west.

McCormick notes that the most valuable slaves were attractive young women and eunuchs, and that Venice was a major center for the castration of slaves. An 840 A.D. treaty between Lothar I (Holy Roman Emperor and grandson of Charlemagne) and the doges of Venice provided that the Venetians would not castrate for sale any of Lothar's subjects. An 880 A.D. revision of the treaty, between Charles III and the doges of Venice, provided only that they would not castrate any citizens of the Holy Romen Empire who were not already slaves when they arrived in Venice.

The preferred source for eunuchs in this period was the still pagan Slavic lands of eastern Europe, though Angles and Saxons from the British Isles were also traded to the east. (Trade in slaves from the British Isles increased at the end of the period and later, with the expansion of the Vikings and a slave trade along the northern route, especially between Dublin and the Caliphate.)

Toward the end of the period under consideration, there was also a lot of slave raiding in the Balkans, with Orthodox Christian monasteries being a preferred target. They were a source for educated boys and young men who could be castrated for sale to the Caliphate, where educated eunuchs found ready employment in the palaces.

Probably not quite the history that you learned in school....

And the people who could trade between the Christian and Muslim worlds were . . .

Da Jews.

Moi

After all, both Christianity and Islam are Jewish heresies.

So the Jews could trade with both.

,,,

JesusA (imported) wrote: Sun Feb 23, 2014 10:09 pm The preferred source for eunuchs in this period was the still pagan Slavic lands of eastern Europe, though Angles and Saxons from the British Isles were also traded to the east. (Trade in slaves from the British Isles increased at the end of the period and later, with the expansion of the Vikings and a slave trade along the northern route, especially between Dublin and the Caliphate.)

Toward the end of the period under consideration, there was also a lot of slave raiding in the Balkans, with Orthodox Christian monasteries being a preferred target. They were a source for educated boys and young men who could be castrated for sale to the Caliphate, where educated eunuchs found ready employment in the palaces.

....

This same topic is covered in a chapter of the book Castration and Society in the Middle Ages.

As to what the Europeans had to offer, try salt. There is a reason that Venice located on a salt marsh became a financial center courtesy of da Jews. (And the reason the marsh is there has to do with plate tectonics.) There were well established trade routes across the Sahara between west Africa and Italy trading gold for salt. Along with that came rumors of a lost Christian colony in west Africa. As seafaring technology made exploration feasible about 1400, the Portuguese set out sailing down the African coast looking for gold and lost Christian colonies (religion was all powerful at that time). They slowly kept going around Africa and India to the Spice Islands in the Pacific, leaving strong points along the way. All that well before Columbus was a gleam in his father’s eye.