We know Kazahstanies often look "mixed" so maybe Scythians began to mix with turkic people and lost their original culture and language. Something similar happened in Anatolia.

I remember reading that original Turkics were racially mostly Caucasian with some Mongoloid influence, but not total Mongols.

Kazakhstan and other Central Asian "stans" have extremely high levels of R1a haplogroup, as well as having mixed Eurasian look, definitely suggests that Eastern white tribes (Iranic, Tocharian, Eastern Germanic, Slavic and original Turkic – despite not being fully white) definitely make up part of their heritage. On other hand, Mongols ravaged this steppe lands and slaughtered off many of them during times of Mongol Empire (especially men in combat), probably also taking local females as wives/booty (at that time probably mostly Caucasian racial type), and therefore over time creating this hybrid of Asian and European peoples known today as Central Asian Turkics.

That's what I think anyway, but I think it sounds logical.

Daurentius reportedly retorted that "Others do not conquer our land, we conquer theirs […] so it shall always be for us", and had the envoys slain. Bayan then campaigned (in 578) against Daurentius' people, with aid from the Byzantines, and set fire to many of their settlements, although this did not stop the Slavic raids deep into the Byzantine Empire.

Hahahaha, this! This has remained in Slavic mentality to this day. Pity we didn't rid Balkans of Albanians when we had chance.