Where came Comb Ceramic Culture R1a from?

[Kmakkmak]

Comb Ceramic Culture have R1a Y DNA. Comb Ceramic Culture is Proto-Indo-European mixed?

[Kmakkmak]

Comb Ceramic Culture, Dnieper Donets Culture and other non-Proto-Indo-European Cultures have rich R1a. What explain it?
This Cultures is Proto-Indo-European mixed?

[tipirneni]

Pontic region

[Kmakkmak]

Pontic region

Pontic region is not culture but area. What do you try saying Pontic region actually?