Other sources from the later times give us the feeling that all those nomad, half-nomad and "said to be Turkish" people like Scythians, Huns, Avars, Bulgars, Kazars, Hungarians etc had the same language.
For example in some writing Christian monks(?) wrote that these people got their translations of the Bible in their Hunnic language. Clearly stating that they had one single language.
The Kazars, especially their leaders adopted the Jewish religion. That's why a rabbi wrote them a letter asking their origin.
The Kazar prince answered that they are not Jews originally, but just adopted that religion. Also he wrote that they are of the 10 sons of Togarmah, a descendant of Japhet. He said the sons then:
In Hebrew:
1. Kozar 2. Pacinak 3. Aliqanos 4. Bulgar 5. Ragbiga (Ragbina, Ranbona)
6. Turqi 7. Buz 8. Zabuk 9. Ungari 10. Tilmac (Tilmic).
In the Arabic translation:
1. Khazar 2. Badsanag 3. As-alān
4. Bulghar 5. Zabub 6. Fitrakh (Kotrakh?) 7. Nabir 8. Andsar (Ajhar) 9. Talmis 10. Adzīgher
He mentions that they are their very close relatives. From these names we can easily recognize: Ungar, Bulgar, Kazar, Alan, Pacinak...
Also mentions that Ungars, Bulgars and Pacinaks live next to the Danube.