Byzantine emperor (610–41). He came to power having ousted the usurper Phocas, and set about the reorganization of the empire and its army, driving back the Persians in Asia Minor and securing a peace treaty. He then turned his attentions to the north, coming to terms with the invading Avars, who had invaded Europe from central Asia, and strengthening the frontier. He then devoted his energies to the study of religion, neglecting the empire and losing Syria and Egypt to the Muslims.