Most subsequent conflicts came as a result of raids by the Avars, or their subject Slavs, into the Balkan provinces of the Byzantine Empire.

As a result, they often raided without resistance for long periods of time, before Byzantine troops could be freed from other fronts to be sent on punitive expeditions.

This happened during the 580s and 590s, where Byzantium was initially distracted in the Byzantine–Sasanian War of 572–591, but then followed up by a series of successful campaigns that pushed the Avars back.

Subject peoples, such as the early Slavs and the Huns, had long traditions of engineering and craftsmanship, such as the building of boats and bridges, and the use of rams, tortoise formations, and artillery in sieges.

[6] Refused, they began pillaging the northern and eastern Balkans, which only ended after the Avars were pushed back by the Byzantines from 597 to 602.

[8] Their rapid spread was facilitated by the ongoing Byzantine–Sasanian War of 572–591, which left the Byzantine garrisons on the Danube frontier under-manned and underpaid.

[8] The Avars and Slavs continued to raid with little resistance until 591, when Emperor Maurice made a ceasefire treaty with the Sassanids in a fairly favorable terms, and shifted his focus to the Balkans.

Priscus' retreat allowed for a new Slav incursion in late 593/594 in Moesia and Macedonia, with the towns of Aquis, Scupi and Zaldapa being destroyed.

Due to his inexperience, Peter suffered initial failures, but eventually managed to repulse the tide of Slav and Avar incursions.

In late August of 594, he crossed the Danube near Securisca and fought his way to the Helibacia river, preventing the Slavs and Avars from preparing new pillaging campaigns.

[11] Priscus, who had been given command of another army, prevented the Avars from besieging Singidunum in 595, in combination with the Byzantine Danube fleet.

[13] Emboldened by the plunder from the Franks, the Avars resumed their raids across the Danube in autumn of 597, catching the Byzantines by surprise.

[15] Due to the threat posed by the Avar forces at Drizipera, Comentiolus was replaced with Philippicus, and recalled to Constantinople.

[17] Maurice then paid off the Avars for a temporary truce,[14] spending the rest of 598 in reorganizing his forces and analyzing how to improve the Byzantines' strategy.

This battle was significant, as it was the first time the Avars suffered a major defeat in their home territory, and also led to the deaths of several more of Bayan's sons.

After the battle, Priscus led his forces north into the Pannonian plain, engaging and defeating the Avars deep within their heartland.

Maurice planned to repopulate the devastated lands which the Byzantines had recovered by settling Armenian peasants, whose homeland was the eastern part opposite to the Western Balkan part in the Empire -It was a deliberately enforced imperial strategy in order to prevent ethnic/tribal consolidation as the independent rebellious forces-, as well as Romanizing the Slavic settlers already in the area.

However, the Sclaveni boats were rammed and destroyed by the galleys of Bonus, and the Avar land assaults on August 6 and 7 were repelled.

[39] At around this point, the news that the Emperor's brother Theodore had decisively defeated Shahin arrived, leading the Avars to retreat to the Balkan hinterland within two days.

[36][37] In thanks for the lifting of the siege and the supposed divine protection granted by the Virgin Mary, the celebrated Akathist Hymn was written by an unknown author, possibly Patriarch Sergius or George of Pisidia.

[40][41] After failing to capture Constantinople, the Avars rapidly began to decline before disintegrating entirely,[42] due to both internal power struggles, and conflicts with the Bulgars and Sclaveni.

[43] After their hegemony over various tribal peoples collapsed, their land was further reduced by the Bulgars around 680, leaving behind a rump state which remained until their conquest by Charlemagne, starting in 790 and ending in 803.