James Burke, writing of the ninth-century AD (the century of Charlemagne’s death in 814 AD):
(p. 32) It was at this time too that anti-Semitism, previously rare, began to increase. Money-lending, which was forbidden by the Christian Church, was permitted under Jewish law, and the Jews, prevented from owning land, turned to the new business currency. Many of them grew rich and were resented.
Burke, James. The Day the Universe Changed: How Galileo’s Telescope Changed the Truth and Other Events in History That Dramatically Altered Our Understanding of the World. Back Bay Books, 1995.