Keszthely culture was created ca. 500 – 700 by the Romanized residents of Pannonia who lived in the area of the fortified village of Castellum (now Keszthely), near Lake Balaton in now western Hungary.
This culture flourished under the Avars' domination of Pannonia and is especially noteworthy for artifacts (mainly of gold) produced by artisans in Keszthely.
At Fenekpuszta [Keszthely] . . . excavations have brought to light a unique group of finds that suggest not only Christians but Romans too. . . . There are finds such as a gold pin with the name BONOSA proving that some ethnic group of Roman complexion remained at Fenekpuszta [after the barbarian invasions]
Pannonia, a province of the Western Roman empire, was devastated by the barbarian invasions (Huns, Gepids, Avars, etc.). Only a few thousand Romanized Pannonians survived the onslaughts, mainly around Lake Pelso (now lake Balaton) in small fortified villages such as Keszthely.
The Romanic population from Pannonia created the Keszthely culture that evolved mainly during the 6th-7th centuries. Its artifacts were made in the workshops of Roman origin located mainly in the fortified settlements of Keszthely-Fenékpuszta and Sopianae (modern Pécs). The Romanic craftsmen worked for their Gepid and Avar masters.
Under the Avars, the Roman castle of Fenékpuszta near Keszthely and the surroundings were not occupied, so the original Romanized inhabitants lived on undisturbed. They paid food and artisan goods for peace from the Avars. After 568 new Christian Romanized Pannonians arrived here, probably from the destroyed Aquincum (modern Budapest). The Keszthely-Fenékpuszta fortress became the centre of a 30 km diameter area, where the people buried their dead adorned with jewellery and clothing of Byzantine origin. They rebuilt the fortress basilica, where the principals of the community were buried, while their relatives found their final resting places next to the nearby horreum (granary). In 626, the Avars were seriously defeated under Constantinople, which was followed by a civil war. The leaders of the Keszthely-Fenékpuszta community had supported those who were later defeated. That was why the Avars besieged and then destroyed the fortress of Fenékpuszta. They made the rest of the Romanized population move into the territory of the town centre. The Christian Romanized population was subjected to military suppression. The cemeteries of the 7th and 8th centuries entombed both Avars and Christians, but they were buried separately. The different religions did not allow them to mix even after death. The Christian Romanized populace, which spoke its own Romance Pannonian language, was cut from the outer world and created a unique, characteristic material culture, which we know from the artifacts of the cemeteries near Keszthely. These finds have been termed Keszthely culture. At that time, Keszthely was the center of the Pannonian region, because the area of Lake Balaton was crossed by roads connecting the Danube and the Mediterranean.