Generally I agree with you. Evidence is needed and strong facts.
It is interesting that there are scientific papers where researches find examples from which something can be done.
One scientific article :
Pavel Serafimov
New Reading of the Thracian Inscription on the Golden Ring from Ezerovo
http://www.korenine.si/zborniki/zbor...mov_ezer07.pdf
The most interesting part of text is from page 180 to 182
New interpretation
In Latin alphabet, Thracian Inscription (originally in Greek):
ROLISTENE AZ NERENEA TILTEANIS KOA RAZEA DO MEAN TI LEZI PTA MIHE RAZIL TA.
Inscription written 2.500 years ago.
For author (and me) it seems quite Slavic/South Slavic (Bulgarian, Serbian etc..., according to author Old Bulgarian is closest).
1.
Rolistene
It is Thracian personal name, Rolisten. In Slavic languages (Bulgarian, Serbian, Czech...) vocative has added e.
For example:
Ivan
Vocative: Ivane
Stanislav
Vocative: Stanislave
Etc.
2)
Az
It is as Old Slavic:
(j)azъ = I (English)
In Bulgarian is: Az (in Serbian is: Ja)
3)
NERENEA
Thracian female name
It is similar as Bulgarian name Neranza. In text there are more explanations.
4)
TILTEANIS
Thracian family name
TIL + TEANIS
a)
Bulgarian,
tilište: human, person (Slavic: čeljade)
In Slavic languages there are words containing "tilište", for example: in Serbian: svetilište: sanctuary.
b)
Bulgarian name Tehan; Bulgarian and Serbian name: Dejan etc.
5)
KOA
Bulgarian/Serbian: koja (j as y in English), similar in another Slavic languages
Sanskrit: kah (Eng. who), etc.
6)
RAZEA
Bulgarian verb: reža (Serbian: rezati) (Eng. to cut, to carve)
Bulgarian none: rez (Serbian: rez, recka) (Eng. notch)
Etc., similar in another Slavic languages
Here is meaning in English: I make lines, I draw.
7)
DO
Bulgarian: Do, Serbian: Do and same or similar in another Slavic languages(Eng. beside, next)
8)
MEAN
Bulgarian: men, mene, me; Serbian: mene, me, and similar in another Slavic languages (Eng., me)
9)
TI
Bulgarian: ti, Serbian: ti, and same or similar in another Slavic languages (Eng. you)
10)
LEZI
Bulgarian: leži; Serbian: leži (imperativ: lezi), and similar in another Slavic languages (Eng. lay)
11)
PTA
Old Bulgarian: Bat; (Eng. Master)
Modern Bulgarian: Bate, Serbian: Bata (Eng. brother)
12)
MIHE
Slavic (general): moj (j as y in English) (Eng. my)
13)
RAZIL
Old Bulgarian: raziti sja; Serbian: razići se; Russian:razoitis; etc. (Eng. go away)
Root: Raz has a lot of words in Bulgarian, Serbian and another Slavic languages
14)
TA
Bulgarian: tuk, Serbian: tu, similar in another Slavic languages (Eng. here)
...
In English: Rolistene, me Nerenea Tilteanis (is the one) who wrote this: lay beside me
my master, (husband) released here (in the grave).
Author concludes:
"
Thracian language was nothing more but arhaic Slavic language."
(Did he conclude this too early or no let everyone judges?)