Which Byzantine emperor wrote the manual 'De Administrando Imperio'?

Constantine VII wrote the Byzantine manual De Administrando Imperio for his son and successor, Romanos II.

Composed in the mid-10th century, probably between about 948 and 952, the work offered practical guidance on ruling the Eastern Roman Empire. It discussed diplomacy, frontier peoples, imperial administration, geography, and the histories of neighboring groups such as the Rus, Pechenegs, Hungarians, Arabs, Armenians, and Georgians.

Constantine VII was known as a scholar-emperor who encouraged learning and commissioned several major works. De Administrando Imperio was likely produced with help from educated court officials, but Constantine’s own instructions, first-person comments, and direct address to Romanos make him the recognized author.

A common mix-up is Basil I, Constantine’s grandfather, whose biography Constantine also commissioned. The manual is valuable precisely because it combines administrative advice with unusually detailed information about Byzantium’s neighbors, though some passages include legends or confused chronology.