Maurice (emperor) in the context of "Maurice's Balkan campaigns"

The Byzantine Empire under the Justinian dynasty began in 518 AD with the accession of Justin I. Under the Justinian dynasty, particularly the reign of Justinian I, the empire reached its greatest territorial extent since the fall of its Western counterpart, reincorporating North Africa, southern Illyria, southern Spain, and Italy into the empire. The Justinian dynasty ended in 602 with the deposition of Maurice and the accession of his successor, Phocas.

The Byzantine Empire's history is generally periodised from late antiquity until the Fall of Constantinople in 1453 AD. From the 3rd to 6th centuries, the Greek East and Latin West of the Roman Empire gradually diverged, marked by Diocletian's (r. 284–305) formal partition of its administration in 285, the establishment of an eastern capital in Constantinople by Constantine I in 330, and the adoption of Christianity as the state religion under Theodosius I (r. 379–395), with others such as Roman polytheism being proscribed. Although the Western half of the Roman Empire had collapsed in 476, the Eastern half remained stable and emerged as one of the most powerful states in Europe, a title it held for most of its existence. Under the reign of Heraclius (r. 610–641), the Empire's military and administration were restructured and adopted Greek for official use instead of Latin. While there was an unbroken continuity in administration and other features of Roman society, historians have often distinguished the Byzantine epoch from earlier eras in Roman history for reasons including the imperial seat moving from Rome to Constantinople and the predominance of Greek instead of Latin.

The borders of the Empire evolved significantly over its existence, as it went through several cycles of decline and recovery. During the reign of Justinian I (r. 527–565), the Empire reached its greatest extent after reconquering much of the historically Roman western Mediterranean coast, including north Africa, Italy, and Rome itself, which it held for two more centuries. During the reign of Maurice (r. 582–602), the Empire's eastern frontier was expanded and the north stabilised. However, his assassination caused a two-decade-long war with Sassanid Persia which exhausted the Empire's resources and contributed to major territorial losses during the Muslim conquests of the 7th century. In a matter of years the Empire lost its richest provinces, Egypt and Syria, to the Arabs.

Byzantine rule in North Africa spanned around 175 years. It began in the years 533/534 with the reconquest of territory formerly belonging to the Western Roman Empire by the Eastern Roman (Byzantine) Empire under Justinian I and ended during the reign of Justinian II with the conquest of Carthage (698) and the last Byzantine outposts, especially Septem (708/711), in the course of Islamic expansion.

The region's administrative structure was initially in line with the typical late Roman administrative structures that had been existing for the past 300 years. Civil powers were thus in the hands of a Praetorian prefect, the head of the supreme civil administrative authority in the Late Roman Empire. The military powers, however, were incumbent on a Magister militum per Africam. These powers were merged into single office from 591 at the latest, and East Roman North Africa became the heartland of one of two exarchates, with the founding of which the East Roman Emperor Maurice (582–602) was able to counteract the consequences of imperial overstretch through bundling and decentralization. No further change in these administrative structures took place until the end of Byzantine rule.

Phocas (Latin: Focas; Ancient Greek: Φωκάς, romanized: Phōkás; 547 – 5 October 610) was Eastern Roman emperor from 602 to 610. Initially a middle-ranking officer in the Roman army, Phocas rose to prominence as a spokesman for dissatisfied soldiers in their disputes with the court of the Emperor Maurice. When the army rebelled in 602, Phocas emerged as the leader of the mutiny. The revolt led to the overthrow and execution of Maurice in November 602.

Phocas deeply mistrusted the uncooperative elite of Constantinople, to whom he was a usurper and a provincial boor. He therefore attempted to base his regime on relatives installed in high military and administrative positions. He immediately faced challenges in domestic and foreign affairs, and responded with little success. He dealt with domestic opposition with increasing ruthlessness that alienated ever wider circles, including some of his own household. The Sasanian Empire launched a massive invasion of the eastern provinces. Finally, the exarch of Africa, Heraclius the Elder, rebelled against Phocas and gained wide support throughout the empire. Phocas attempted to use border troops to crush the rebellion, but this only resulted in allowing invaders to break into the heartlands of the Empire. Heraclius the Elder's son, Heraclius, took Constantinople on 5 October 610, executed Phocas the same day, and declared himself emperor.

Khosrow II (spelled Chosroes II in classical sources; Middle Persian: 𐭧𐭥𐭮𐭫𐭥𐭣𐭩, romanized: Husrō and Khosrau), commonly known as Khosrow Parviz (New Persian: خسرو پرویز, "Khosrow the Victorious"), is considered to be the last great Sasanian King of Kings (Shahanshah) of Iran, ruling from 590 to 628, including an interruption of one year.

Khosrow II was the son of Hormizd IV (reigned 579–590), and the grandson of Khosrow I (reigned 531–579). He was the last king of Iran to have a lengthy reign before the Muslim conquest of Iran, which began five years after his execution. He lost his throne, then regained it with the help of the Byzantine emperor Maurice, and, a decade later, went on to emulate the feats of the Achaemenids, conquering the rich Roman provinces of the Middle East; much of his reign was spent in wars with the Byzantine Empire and struggling against usurpers such as Bahram Chobin and Vistahm.

Pope Gregory I (Latin: Gregorius I; Gregorio I; c. 540 – 12 March 604), commonly known as Saint Gregory the Great (Latin: Sanctus Gregorius Magnus; Italian: San Gregorio Magno), was the 64th Bishop of Rome from 3 September 590 until his death on 12 March 604. He is known for instituting the first recorded large-scale mission from Rome, the Gregorian mission, to convert the then largely pagan Anglo-Saxons to Christianity. Gregory is also well known for his writings, which were more prolific than those of any of the previous popes. The epithet Saint Gregory the Dialogist has been attached to him in Eastern Christianity because of his Dialogues. English translations of Eastern texts sometimes list him as Gregory "Dialogos" from the Greek διάλογος (dialogos, conversation), or the Anglo-Latinate equivalent "Dialogus". He is the second of the three Popes listed in the Annuario Pontificio with the title "the Great", alongside Popes Leo I and Nicholas I.

A Roman senator's son, and himself the prefect of Rome at 30, Gregory lived in a monastery that he established on his family estate before becoming a papal ambassador and then pope. Before becoming Pope, he challenged the theological views of Patriarch Eutychius of Constantinople before the emperor Tiberius II. Although he was the first pope from a monastic background, his prior political experiences may have helped him to be a talented administrator. During his papacy, his administration greatly surpassed that of the emperors Maurice and Theodosius in improving the welfare of the people of Rome. Gregory regained papal authority in Spain and France and sent missionaries to England, including Augustine of Canterbury and Paulinus of York. The realignment of barbarian allegiance to Rome from their Arian Christian alliances shaped medieval Europe. Gregory saw Franks, Lombards, and Visigoths align with Rome in religion. He also combated the Donatist heresy, popular particularly in North Africa at the time.

Heraclius the Elder (Greek: Ἡράκλειος, romanized: Hērákleios; died 610) was a Byzantine Roman general and the father of Byzantine Roman emperor Heraclius (r. 610–641). Heraclius the Elder distinguished himself in the war against the Sassanid Persians in the 580s. As a subordinate general (or hypostrategos), Heraclius served under the command of Philippicus during the Battle of Solachon and possibly served under Comentiolus during the Battle of Sisarbanon. Circa 595, Heraclius the Elder is mentioned as a magister militum per Armeniam sent by Emperor Maurice (r. 582–602) to quell an Armenian rebellion led by Samuel Vahewuni and Atat Khorkhoruni. Around 600, he was made the exarch of Africa and in 608, he rebelled with his son against the usurper Phocas (r. 602–610). Using North Africa as a base, the younger Heraclius managed to overthrow Phocas, beginning the Heraclian dynasty, which would rule Byzantium for a century. Heraclius the Elder died soon after receiving news of his son's accession to the Byzantine throne.