A paper that rebuilt early medieval trade routes from where ancient coins were buried finds that after the Arab conquests of North Africa and Spain, Europe's wealth shifted from Italy and the Balkans to France and Germany.
The author is an unabashed free trader, worried by the protectionist turn, and reaches for a paper in which two economists did something unusual: they traced trade routes by digging up ancient coins.
Where the coins were buried, the routes ran
Late in the Roman Empire the economic centre moved east to Byzantium; after the Visigoths sacked Rome in 410, western and northern Europe slid downhill. In the seventh century the Arabs took North Africa, and by the early 700s much of Spain.
Mints across Europe and the Middle East kept striking coins, and traders carried them around. Where a coin ended up buried is roughly where the trade went.
A new border, and the business reroutes
The researchers compared two stretches: 450 to 630, and 713 to 900, after the Arab conquests.
With a frontier between the Christian and Muslim worlds, Byzantium — today's Turkey and southeast Europe — was pushed ever further out of the trading network.
At the same time, traffic flowed towards modern-day France and Germany through Muslim routes across North Africa and into Spain.
Who got richer, who got poorer
Money follows trade and people follow money. Consumption fell in Italy, the Balkans and Turkey, and rose fast in France and Germany.
Where consumption rose, cities grew. Between 700 and 900, urban populations climbed in exactly that region.
Cities were trading hubs where new ideas spread quickly and work got more productive, which made them richer — the same logic that holds today.
The newly rich lands paid for the armies of Pippin and his son Charlemagne, and the Carolingian Empire dominated Europe for a thousand years. If you live in Germany, France, the Netherlands, Belgium or Britain, you owe the Arabs who took North Africa and Spain a measure of thanks.
Why it matters
Trade routes do more than move goods: they decide which land grows cities, funds armies and ends up ruling for centuries. Today's arguments over supply chains and borders are drafting the same answer — it just takes a few hundred years to read it.
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