The reign of Khosrau II (591-628) is characterized by the wasteful splendor and lavishness of the court.

Khosrau II's power declines toward the end of his reign.

In fighting with the East Roman, or Byzantine, Empire (the successor to the eastern half of the Roman Empire), he enjoys initial successes, captures Damascus, and seizes the Holy Cross (upon which Christ presumably was crucified) in Jerusalem, but counterattacks by the emperor Heraclius bring enemy forces deep into Sassanian territory.

Years of warfare exhaust both the Greeks and the Iranians.

The later Sassanians are further weakened by economic decline, heavy taxation, religious unrest, rigid social stratification, the increasing power of the provincial landholders, and a rapid turnover of rulers.

These factors will facilitate the Arab invasion later in the seventh century.

The Middle East: 580–591 CE

The Byzantine–Sassanian War and Cultural Developments

Prolonged Imperial Conflict

From 580 to 591 CE, the conflict between the Eastern Roman Empire (Byzantine Empire) and the Sassanian Empire of Persia, known as the Byzantine–Sassanian War (572–591), continues with relentless intensity. This war forms part of a broader pattern of hostilities spanning the sixth and early seventh centuries, notable for battles largely confined to frontier regions including Mesopotamia, Greater Armenia, and Syria. Despite continuous military engagements, neither empire manages to sustain a decisive hold over territories deep within enemy lines, marking this era as the final stage of relatively restricted frontier warfare before wider-ranging conflicts emerge in the subsequent decades.

Treaty and Territorial Realignments

The long conflict culminates with the restoration of the Persian king Khosrau II to his throne in 591 CE. In return for the crucial support from Constantinople, Khosrau II cedes most of Persian-controlled Armenia and the western half of Caucasian Iberia to the Byzantines. This significant territorial realignment stabilizes the region temporarily, reestablishing spheres of influence that would profoundly shape subsequent political and military interactions.

Cultural Achievements Amid Turbulence

Remarkably, the period witnesses minimal artistic production due to sustained instability and warfare. Nevertheless, one significant cultural artifact survives: the Rabula Gospels, an illuminated manuscript completed in 586 CE at Zagba in Syria. Distinguished by its elaborate architectural and floral motifs, the manuscript exemplifies a vibrant yet sketchy, informal style characteristic of early Byzantine illuminated manuscripts—rare survivors of this turbulent era.

Ghassanid Influence and Cultural Patronage

Amidst imperial conflicts, the Ghassanids, Arab allies of Constantinople, continue to prosper culturally and economically. They engage in substantial religious and public construction and actively patronize poets such as Nabighah adh-Dhubyani and Hassan ibn Thabit. Nonetheless, their Monophysite beliefs draw suspicion from orthodox Byzantine leaders, resulting in reduced autonomy and direct imperial intervention. This cultural and religious friction underscores the complex interplay of local autonomy and imperial control characteristic of the region during this transformative period.

The Byzantine–Sassanid War of 572–591 is part of an intense sequence of wars between the East Roman and Sassanid Persian empires that occupy the majority of the sixth and early seventh centuries.

It is also the last of the many wars between them to follow a pattern in which fighting is largely confined to frontier provinces (in Mesopotamia, Greater Armenia, and Syria) and neither side achieves any lasting occupation of enemy territory beyond this border zone.

It precedes a much more wide-ranging and dramatic final conflict in the early seventh century.

The result is the restoration of Khosrau II to the Sasanian throne in 591; Khosrau II gives the Constantinople-based Empire most of Persian Armenia and the western half of Caucasian Iberia.

The truce in Mesopotamia had come to an end in 578 and the main focus of the war shifted to this front.

After Persian raids in Mesopotamia, the new magister militum of the East, Maurice, who had first entered the imperial government as a notary, leads an effective campaign against Persia on the eastern frontier.

Mounting raids on both sides of the Tigris, captures the fortress of Aphumon and sacks Singara.

Khosrau had again sought peace in 579, but died before an agreement could be reached and his successor Hormizd IV had broken off the negotiations.

The Ghassanids score yet another victory over the Lakhmids in 580, while imperial raids again penetrate east of the Tigris.

Around this time, however, …

…the future Khosrau II is put in charge of the situation in Armenia, where he succeeds in persuading most of the rebel leaders to return to Sassanid allegiance, although …

…Iberia remains loyal to Constantinople.

Mundhir goes in the summer of 580 or 581 to Circesium on the river Euphrates, where he joins the imperial forces under the new magister militum per Orientem, Maurice, for a campaign deep into Persian territory.

The combined force moves south along the river, accompanied by a fleet of ships.

The allied army storms the fortress of Anatha and moves on until it reaches the region of Beth Aramaye in central Mesopotamia, near the Persian capital of Ctesiphon, but there they find the bridge over the Euphrates destroyed by the Persians.

With any possibility of a march to Ctesiphon gone, they are forced to retreat, especially since at the same time …

…the Persian commander Adarmahan has taken advantage of the imperial army's absence and is raiding freely in Osroene, where he sacks the provincial capital Edessa.

The retreat is arduous for the exhausted army, and Maurice and Mundhir exchange recriminations for the expedition's failure.

Mundhir and Maurice cooperate, however, in forcing Adarmahan to withdraw, and defeat him at Callinicum.