"This book examines the way in which Christianity spread throughout the known world in the Middle Ages and also explores the great variety of forms which it took. It spans the centuries from A. D. 312, when Constantine the Great ended the persecution of the Church, to 1500, when European overseas expansion inaugurated a period of Western religious dominance. In the medieval centuries Christianity spread throughout Western Europe and was taken by the Vikings to Iceland and Greenland and even perhaps the north American mainland. From the Holy City of Byzantium, Orthodox Christianity spread northwards into Bulgaria, Serbia and Russia. In North Africa there were large Christian communities living under Muslim rule, while in the Sudan and Ethiopia there were independent Christian kingdoms. The Christians of South India claimed to have been converted by the Apostle Thomas, while Christians from Persia evangelized nomadic tribes in central Asia living along the silk road leading to China. " -- Publisher's description.