Yes. There are many proofs who relate Bulgarian language with other Iranics. Literally, Slavic nations and Iranic nations are historical brothers. Specially by origin and language.
Turks are some different civilisation from them.
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Only Scytho-Sarmatians are responsible for the linguistic and cultural connection to the Slavs in terms of borrow words, other Iranic populations were way too remote.
By linguistic terms, older Iranian dialects have a good share of similar words, don't remember them all but there are quite few.
its because they settled there many millenias before modern era.
http://alterling2.narod.ru/English/Maps/BulgarsE.PNG
http://alterling.ucoz.de/_si/0/s08183770.jpg
https://i.imgur.com/TYUauXa.png
On the map, purple dots mark localities with Bulgarish origin of the name, which may correspond to the times of CWC or close to them. Maroon – the later, of Scythian period. Asterisks mark known single or group sites of CWC. Browns show the area of Indo-Europeans, and green is the territory of the spread Fatyanovo and Balanovo cultures. Hydronyms of Bulgarish origin are indicated by turquoise dots.
but please note - those similarities only between Iranic and South Slavic
Klyosov from the same paper: "Те же языки, в своем развитии, составляли неИЕ языки древней Европы, которые от современных молодых тюркских, конечно, ушли уже очень далеко, и которые до сих пор составляют мощный «доИЕ субстрат» в европейских языках, в частности, в германских."
Google Translate: "The same languages, in their development, were the non-IndoEuropean languages of ancient Europe, which of course from the modern young Turkic countries have already gone very far, and which still constitute a powerful "pre-IndoEuropean substratum" in European languages, in particular, in Germanic."
look up: --> Chuvash-Germanic lexicon