Pax Nicephori

Pax Nicephori, the "Peace of Nicephorus", is a term used to refer to both a peace treaty of 803, tentatively concluded between the Frankish ruler Charlemagne and Nikephoros I, Basileus of the Eastern Roman Empire, and the outcome of negotiations that took place between the same parties, but were concluded by successor emperors, between 811 and 814. The whole set of negotiations of the years 802–815 AD has also been referred to by this name. By its terms, after several years of diplomatic exchanges, the Byzantine emperor's representatives recognized the authority in the West of Charlemagne, and East and West negotiated their boundaries in the Adriatic Sea.

On Christmas Day in 800 AD, the Pope Leo III crowned Charlemagne as Imperator Romanorum (Latin for "Emperor of the Romans") in Saint Peter's Basilica. Nikephoros I of the Byzantine Empire and Charlemagne tried to settle their imperial boundaries in 803. A first treaty was indeed prepared and sent to the East in 803 by Charlemagne, who had started talks with Empress Irene. The text, however, was never ratified by Nikephoros, as the Royal Frankish Annals, and Charlemagne in a surviving document, explicitly state. The Franks had already subdued the March of Istria in 788, and after overturning the Avar khaganate, they claimed the rich Pannonian plain and the Dalmatian coast; during these events, Slavic prince Vojnomir of Pannonia allied with the Franks.Dalmatian Croatia, located in what was nominally Byzantine Dalmatia, peacefully accepted limited Frankish overlordship.

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