Cambridge为何译为剑桥

Cambridge为何译为剑桥 地名的称呼是历史的渊源:
A municipal borough of east-central England on the Cam River north-northeast of London. It is an ancient market town and the site of Cambridge University, established in the 12th to 13th century. Population, 100,200.
剑桥：英格兰中东部的一座享有自治权的市镇，靠近剑河且位于伦敦市东北偏北。它是古代的一座城镇，也是剑桥大学所在地，建于12到13世纪。人口100,200