Constantine VII, called Porphyrogennetos because he was born "in the purple" to a reigning emperor, was Roman Emperor and Caliph of Islam from 912 to 959. The son and successor of Leo VI, he is said to have preferred to have dedicated his life to scholarly pursuits rather than wielding executive authority. However, after the failure of an attempted coup by the regent Romanos Lekapenos, Constantine took command himself and quickly set about eliminating all his remaining rivals.

In 927 he repelled a Bulgarian invasion of Galatia and, as part of the ensuing peace negotiations, he married Zoe, daughter of the Bulgarian emperor. The Roman and Bulgar empires had long been in dispute over the Bulgarian use of the imperial title, and Constantine and his counterpart hoped to resolve the argument by uniting the two under one ruler. However, their plans came to naught as Zoe died childless just a few years later, and the Bulgarian throne was later taken by her brother Boris II.

In the east, Constantine was more successful, intervening in the civil wars that presaged the collapse of the Sassanid Empire and managing to capture much of Assyria. He failed, however, to subjugate Armenia, which would later expand into the region to become a great power.

Under Constantine's reign, Africa, formerly a separate kingdom ruled by his ancestors, was gradually absorbed into the Roman Empire proper, until by the end of his rule it had become little more than a province like any other. In 955 he was forced to put down a rebellion led by his cousin Amalric, with the result that Africa would not regain its independence until the Italian Wars of the 17th century.

Constantine died in 959. He was succeeded by his son, Romanos I.

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