This article examines the term ‘Byzantine’ as it appears in the 678 Sacra of Constantine IV to Pope Donus. Unlike most other late antique and medieval usages of the term, that is, to describe individuals from Constantinople, the Emperor used the term in relation to Palestinian, Cilician and Armenian monastic communities in Rome. The article considers a number of possible readings of the term and suggests that, in the context of distinction between Eastern and Western Romans, the term functioned as a designation for Eastern Romans.