Migration post First Bulgarian Kingdom was in a West>East direction all of these PH908 branches in the East are in my opinion due to migration from the West. I used to think maybe the Morava as well as the Timok basin were PH908 heavy during the First Kindom but now i think its way more likely PH908 migrated from the North to the Timok basin and the Dinaric Alps leaving the South Morava/Kosovo region largely Non-Slavic until the Bulgarian expansion to the west hence the Serb Z17855/YP417 branches. I think these two are very likely Timochani branches > https://www.yfull.com/tree/I-FT277965/ https://www.yfull.com/tree/I-FT138628/
Based on historical sources, we know what was the mood and tribal character of Timocani towards the Bulgarians, primarily thanks to the Frankish court chronicler Einhard, who gives the first written source about this tribe, where he noted their arrival in 818 before Emperor Louis the Pious: "
Legati Abodritorum ac Bornæ, ducis Guduscanorum et Timocianorum ”(envoys from Branicevo and Borna, princes of Kucani and Timocani), in order to seek protection and make an alliance against the Bulgarians. In 827, Omurtag organized a campaign and incursion into the lands of Timocani near Sirmium, after which, taking refuge from the Bulgarian expansion, Timočani migrated to the Lower Pannonian principality, and most likely to the countries of Bosnia, Zahumlje, ie
Dalmatia. Also known are historical testimonies, several Frankish sources
Vita Hludowici imperatoris, Annales regni Francorum, Annales Sithienses, in which Prince Borna is mentioned as the joint prince of Timocani and Guduscan (
dux Guduscanorum et Timocianorum), who was awarded the title in 819. Dalmatia , 821. in the sources stands the
dux Dalmatiae atque Liburnia, where the French gave him a princely position.
So, it is completely illusory to look for the descendants of these tribes among today's Bulgarians, unless you foresee, like me, the transfer of a small number of members of these tribes to the Bulgarian corps, during their struggles and defeats against the Bulgarians?