Although the Muslim commercial web possessed many advanced features, including bills of exchange, sophisticated lending institutions, and futures markets, no Islamic state ever established the bedrock financial institution of the modern world: a national or central bank

Dramatic conquests often lead to startling serendipities: the most momentous Muslim acquisition at Talas was not territory or silk, but a commodity at once prosaic and precious. Among the Chinese prisoners taken at Talas were papermakers, who soon spread their wondrous craft into the Islamic world, and then to Europe, changing forever human culture and the course of history.

For most of the period following the fall of Rome, the adherents of a powerful new monotheistic religion dominated medieval long distance commerce as completely as the West dominates such commerce today; the legacy of that former dominance is still all too visible.

The Umayyad and Abbasid empires were in effect large free-trade areas in which old borders and barriers had been swept away, especially along the Euphrates River, since remotest antiquity the traditional frontier between the East and West. No longer were the three great routes to Asia—the Red Sea, the Persian Gulf, and the Silk Road— competing alternatives; rather, they were an integrated global logistic system available to all parties who recognized the suzerainty of the caliphate.