The Avar Khaganate ruled the Carpathian basin from the 560s to about 800, extorted a fortune in gold from Constantinople, and was destroyed by Charlemagne.
The Avars were a steppe people who arrived on the Danube in the 560s and held the Carpathian basin — roughly modern Hungary and its neighbours — until Frankish armies broke them in the 790s. For most of that time they were the dominant military power in central Europe.
They are unusually hard to write about. They produced no chronicles, no inscriptions and no literature, so every statement about their politics comes from Constantinople or from Frankish annals, both hostile. What they did leave is graves: something on the order of sixty thousand Avar-period burials have been excavated in the Carpathian basin, which makes them among the best-documented peoples of early medieval Europe archaeologically and among the worst documented politically.
Their relationship with the eastern Roman empire ran on gold. For fifty years they were paid not to attack, and the sums grew; when the payments and the threats stopped working, they came to the walls of Constantinople in 626 and were beaten there.
The Avars appear in Byzantine sources in 558, when an embassy reached the emperor Justinian I asking for land and payment. They had come west across the steppe, and later Turkic rulers insisted to Constantinople that these were runaways from the Turkic khaganate rather than the true Avars at all — a dispute the Roman court found politically useful and could not settle.
Justinian did what Roman governments habitually did with new arrivals on the frontier: he paid them and pointed them at somebody else. They fought the Utigurs and Kutrigurs on Rome's behalf, then moved west up the Danube looking for land of their own.
A 2022 study of ancient DNA from elite Avar burials found close affinity with populations of the Mongolian steppe, consistent with a rapid migration westward within a few generations rather than a slow drift. That is a strong result for the ruling group specifically, and says nothing about the mass of the khaganate's subjects, who were mostly local and increasingly Slavic.
The opportunity came from a quarrel between two other peoples. The Lombard king Alboin was fighting the Gepids for control of the middle Danube, and in 567 he bought Avar help on terms that gave them the Gepid lands. The Gepid kingdom was destroyed and never re-formed.
The following year the Lombards left for Italy, and whether they went because Alboin had already decided to or because he had understood what he had just invited into the neighbourhood, the effect was the same: the Avars inherited the whole Carpathian basin without further fighting.
The strategic consequence for Constantinople was immediate. From the middle Danube an Avar army could reach the Balkan provinces in a single season, and the fortress city of Sirmium — the key to the Save frontier — fell to them after a long blockade in 582.
Authority rested with the khagan, and beneath him the khaganate was a coalition rather than a state: Avar horsemen at the centre, and subject Gepids, Bulgars and above all Slavs supplying infantry, labour and boats. The Slav monoxyla that fought in the Golden Horn in 626 were built by subjects, not by Avars.
Its economy was extraction. Tribute from Constantinople rose from 80,000 gold solidi a year under Tiberius II to around 120,000 by the early seventh century, and the sums are recorded because the Roman treasury regarded them as a scandal. Plunder, ransom and the sale of captives supplied the rest.
Militarily the Avars were mounted archers with lamellar armour and a long tradition of composite bows, and they are generally credited with introducing the iron stirrup into Europe in the later sixth century. Byzantine writers paid them the compliment of imitation: the Strategikon attributed to the emperor Maurice tells Roman cavalry to adopt Avar equipment by name.
The ruler list is four names, and the reason is worth stating plainly: the Avars wrote nothing, so a khagan is recorded only when a Greek or Latin author had occasion to mention him.
Bayan I is the one figure who can be followed. He led the Avars into the Carpathian basin, destroyed the Gepids in 567, took Sirmium in 582 and set the pattern of tribute-taking that lasted for decades; he ruled from about 562 until around 602 and was succeeded by his sons.
After him the record thins to almost nothing. The khagan who besieged Constantinople in 626 — the most consequential Avar of all — is named by no surviving source. At the other end, the Frankish annals record a tudun who submitted to Charlemagne in 795 and a khagan called Zodan who came in to the emperor in 803, and both appear only as the men who ended it.
From the 580s the Avars raided the Balkans repeatedly, and the emperor Maurice's attempts to push them back across the Danube were among the causes of the mutiny that killed him in 602. His murder started the Persian war, and the Avars spent the next quarter-century exploiting it.
At a meeting near Herakleia, which the sources place in either 617 or 623, the khagan tried to seize Heraclius in person during a parley. The emperor escaped to the city in disguise, and the episode did more than any raid to establish that no agreement with the Avars was worth anything.
The high point was 626, when the khagan brought his army to the Theodosian walls in coordination with a Persian force at Chalcedon. It was the only time the Avars attempted a full siege of the capital, and the ten days it lasted ended their period of ascendancy.