You have Venetian sources from 1527 where is written than population of Dalmatiam hinterland from 60 000 fell on only 2000 due to Ottoman invasion.
I2-Din among Burgenland Croatians can be for Serbian minority which lived in Croatia before Ottomans. They joined to Croatian in migrations when Ottomans arrived.
How you explain that Burgenland Croatian Dobrović who is I2-PH908 (580 on tabele)
https://lundiak.files.wordpress.com/...outh_ph908.png have a match with Serbs from this various places/region: Njegiši (Montenegro), Priština (Kosovo), Gacko (Easrt Herzegovina), Lovinac (Lika), Kordun, Brod (N. Bosnia), Bijelo Polje (Montenegro), Prijepolje (Raška), Kragujevac (Šumadija), Novi Pazar (Raška), Bru and Aleksandrovac (Central Serbia), Čačak (Central/Western Serbia), Drvar (Eestern Bosnia), Rača (Šumadija)? Wh Croatians would migrated to east in Central Serbia, Šumadija, Kosovo and Raška when Turks came from east and why they would became Serbs?