His father was Flavius Constantius, a native of Dardania province of Moesia (later Dacia Ripensis ). Constantius was a tolerant and politically skilled man. Constantius was an officer in the Roman army, part of the Emperor Aurelian 's imperial bodyguard.

His father was Flavius Constantius, a native of Dardania province of Moesia (later Dacia Ripensis ). Constantius was a tolerant and politically skilled man. Constantius was an officer in the Roman army, part of the Emperor Aurelian 's imperial bodyguard.