The Byzantine–Sasanian War of 602–628 was the final and most devastating of the series of wars fought between the Byzantine Empire and the Sasanian Empire of Iran. The previous war between the two powers had ended in 591 after Emperor Maurice helped the Sasanian king Khosrow II regain his throne. In 602 Maurice was murdered by his political rival Phocas. Khosrow proceeded to declare war, ostensibly to avenge the death of Maurice. This became a decades-long conflict, the longest war in the series, and was fought throughout the Middle East: in Egypt, the Levant, Mesopotamia, the Caucasus, Anatolia, Armenia, the Aegean Sea and before the walls of Constantinople itself.
The Byzantine–Sasanian War of 572–591 was a war fought between the Sasanian Empire of Persia and the Eastern Roman Empire, termed by modern historians as the Byzantine Empire. It was triggered by pro-Byzantine revolts in areas of the Caucasus under Persian hegemony, although other events contributed to its outbreak. The fighting was largely confined to the southern Caucasus and Mesopotamia, although it also extended into eastern Anatolia, Syria, and northern Iran. It was part of an intense sequence of wars between these two empires which occupied the majority of the 6th and early 7th centuries. It was also the last of the many wars between them to follow a pattern in which fighting was largely confined to frontier provinces and neither side achieved any lasting occupation of enemy territory beyond this border zone. It preceded a much more wide-ranging and dramatic final conflict in the early 7th century.
After decades of inconclusive fighting, Emperor Maurice ended the Byzantine–Sasanian War of 572–591 by helping the exiled Sasanian prince Khosrow, the future Khosrow II, to regain his throne from the usurper Bahrām Chobin. In return the Sasanians ceded to the Byzantines parts of northeastern Mesopotamia, much of Persian Armenia and Caucasian Iberia, though the exact details are not clear. More importantly for the Byzantine economy, they no longer had to pay tribute to the Sasanians. Emperor Maurice then began new campaigns in the Balkans to stop incursions by the Slavs and Avars.
Kardarigan (Καρδαριγάν) was a Sassanid Persian general of the late 6th century, who fought in the Byzantine–Persian War of 572–591. Since he is recorded as being old enough to have an adult nephew in 586, it is uncertain whether he is the same as the general of the same name who fought in the later wars of the early 7th century. His name is actually an honorific title and means "black hawk".
In the reign of Justinian I ((r. 527 – 565)), Slavic tribes (Sclaveni) had already appeared on the Danube frontier of the Byzantine Empire. Over the next few decades, they raided into Thrace and Illyricum, while at times serving as mercenaries in the Byzantine army. From the 560s, the Slav communities came under the control of the newly established Avar Khaganate. Raids became larger and resulted in permanent settlement, especially as the Avars were able to capture fortified cities, leading to loss of imperial control over the surrounding areas. While the Byzantines were preoccupied in the East against the Persians, the 580s saw ever deeper and more destructive raids in the Balkans, even into southern Greece. The same period saw the start of large-scale Slavic settlement in the Balkan hinterland. After making peace with Persia, Emperor Maurice was able to launch a series of counterattacks that drove the Avars and their Slavic allies back, but the respite was short-lived: following the usurpation of Phocas in 602, and the start of another, and even more catastrophic, war with Persia, the Balkans were left nigh defenceless, and the Danube frontier collapsed for good, overrun by the Avars and Slavic tribes, who settled across the region.