MIDDLE AGES. The period preceding the Renaissance. Once taken to date from A.D. 476, the fall of the Roman Empire, it is now more correctly held to begin about 1100 and extend to the end of the fifteenth century. Also once viewed as a sterile period, it has come to be recognized as one of the most cultivated and productive eras of human history. It was the age that reached the highest realization of Christendom as a cultural unity built on a common faith.