Nomads whose state was destroyed by the Franks at the end of VIII?

It was the Avar Khaganate, it was located mainly on the territory of modern Hungary, since it is a plain, which is surrounded by mountains on all sides.

The confrontation between the Franks and Avars began in 788. It was then that an alliance was formed with the Bavarians against the Franks, but this quickly ended in defeat.

In 791, the campaign of Charlemagne began (then he was still king, there were still 9 years to the title of emperor), Slavs, for example, modern Croats and Slovenes, took part in it.

The Avars did not have stone fortresses, but there were wooden (hring) fortresses, the main one was probably located on the territory of modern northwestern Romania.

The war went on until 803, and then the Bulgarians hit the Avars.