If Kosovars are the original people of the Balkans, the strongest candidate for IE Thracians would be R1b, not J2b , J2a, or even E-V13. These are basically Middle Eastern people who have nothing to do with the steppes. It can't go both ways
*)
quote-E-V13 has been shown to have originated most probably in the Balkans circa 9000 BCE as a Mesolithicmarker,-end quote
http://digitalcommons.wayne.edu/cgi/viewcontent.cgi?article=1043&context=humbiol_preprints (in reference to
Battaglia et al. 2008) http://www.draganprimorac.com/wp-content/uploads/2010/05/Battaglia.pdf
*)What is proposed in regards to Thracian origins?
It is generally proposed that a proto-Thracian people developed from a mixture of indigenous peoples and Indo-Europeans from the time of Proto-Indo-European expansion in the Early Bronze Age[7] when the latter, around 1500 BC, mixed with indigenous peoples.[8] We speak of proto-Thracians from which during the Iron Age[9] (about 1000 BC) Dacians and Thracians begin developing.
https://en.wikipedia.org/wiki/Thracians#Origins_and_ethnogenesis
*)
Albanian is considered to have evolved from an ancient Paleo-Balkan language, usually taken to be either Illyrian or Thracian. (See also Thraco-Illyrian and Messapian language.)
https://en.wikipedia.org/wiki/Albanian_language
*) Current HG % in the region
Bulgaria
Most Bulgarians belong to three unrelated Y-DNA haplogroups, 20% of whom to I-M423 (I2a1b), 18% to E-V13 (E1b1b1a1b1a) and 17.5% to R-M17 (R1a1a), but the biggest part belongs to macro-haplgoroup R (~28%)
Albania
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[TR]
[TD="align: center"]
N[/TD]
[TD="align: center"]
E-M78*[/TD]
[TD="align: center"]
E-V13[/TD]
[TD="align: center"]
E-M81[/TD]
[TD="align: center"]
E-M123[/TD]
[TD="align: center"]
J2b[/TD]
[TD="align: center"]
I1[/TD]
[TD="align: center"]
I2a2[/TD]
[TD="align: center"]
R1b[/TD]
[TD="align: center"]
R1a[/TD]
[TD="align: center"]
P[/TD]
[/TR]
[TR]
[TD]114[/TD]
[TD]1.75%[/TD]
[TD]43.85%[/TD]
[TD]0.90%[/TD]
[TD]0.90%[/TD]
[TD]16.70%[/TD]
[TD]5.31%[/TD]
[TD]2.65%[/TD]
[TD]21.10%[/TD]
[TD]4.42%[/TD]
[TD]1.77%[/TD]
[/TR]
[/TABLE]
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[TR]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
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It dose not seem like 3500ybp there was such a thing as either or. or cannot go both ways.