Boris I of Bulgaria
In 860 AD, Pope Nicholas I wrote a letter to Boris I of Bulgaria in reply to questions regarding differences between Roman Catholic and Eastern Orthodox practices. Pope Nicholas describes how in the Western church the man gives his betrothed an engagement ring. At the Fourth Council of the Lateran in 1215, convoked by Pope Innocent III, the banns of marriage was instituted, prohibiting clandestine marriages and requiring that marriages be made public in advance. Some legal scholars have seen in this a parallel with the engagement-ring tradition described by Pope Nicholas I.