When did the Avars, Khazars, Bulgars, Byzantines exist?

The Avar tribes existed in central Europe as early as the 6th century. They disappeared around the 9th century, that is, they became part of the Hungarians.

The Khazar tribes existed from the 6th to the 10th century. In the 10th century, the Khazar Kaganate was destroyed by Prince Svyatoslav.

The Bulgar tribes appeared on the Volga around the 4th century. Then there was their resettlement. Thus, the Bulgars were divided into Bulgarians (who lived below the Danube) and Bulgars (on the Volga). Bulgarians still exist.

The Byzantines are Greeks. The very definition of Byzantines is broad, since it does not denote a specific ethnic group or people.