In the western Balkans you can find men with diverse ethnic backgrounds living in relatively close proximity to one another.
Four men who are positive for a branch of J2b-Z1043 known as J2b-FT117099 exhibit this modern ethnic diversity yet their male line ancestors' geography is consistently SW Balkans, north of predominantly ethnic Greek areas.
Their common ancestor is estimated by YFull (v9.05) to have lived around 600 BCE. J-FT117099 on YFull.
I have added the Balkan samples of this lineage to the map, also indicating the recently published ancient J-Z1297* sample, I26726, from Gudnja cave, Croatia dating to about 1200 BCE.
The Balkan Turk, SRS8752540, I have represented with a bigger circle around Thessaloniki because, while this anonymous sample from a scientific study did not indicate his male line origin, 58% of his autosomal DNA was demonstrated by researchers to match a population labeled Greek_Thessaloniki [source].
This Balkan Turk shares 11 SNPs with the Sandžak Bosniak, which may indicate a MRCA that lived in the first few centuries of the Common Era. We expect an estimate in January when YFull updates to v9.06.
Because of the potential for these samples to reveal a geographically consistent origin for an Iron Age lineage of J2b-Z631, notorious for its geographic inconsistency, we decided to use research project donations to upgrade the Pukë -> Preševo ethnic Albanian sample to Big Y.
While we are waiting on the results, his 111 STRs have finished processing. Below is the STR Match Finder output indicating three rare alleles that he and the man tracing descent to a Macedonian speaker from Bitola, North Macedonia likely inherited from a more recent common ancestor.
These two men differ on 18 of 111 STRs. We are waiting for the Big Y to finish. Then we'll have his sample analyzed by YFull and added to their tree. This Albanian guy accumulated a large number of mutations among the more stable alleles. It'll be interesting to see how many SNPs they share and when their MRCA is estimated to have lived. Their paternal line geography is the closest within this group.
Factors Obscuring the Geographic Origin of J2b-Z631 MRCA from 900 BCE
There are a number of factors obscuring where the J2b-Z631 MRCA was living.
The Iron Age was a time of great mobility across the Adriatic and Ionian Seas.
Celtic groups migrated into the Balkans. Though they may have eventually mixed with the indigenous tribes, there is a chance that some indigenous J2b-Z631 may have been killed, displaced or had lower reproductive fitness if some Celtic lines had higher status in the Scordisci polities.
During the reign of Augustus, the Romans killed or enslaved much of the indigenous western Balkan population that rebelled in the Bellum Batonianum 6-9 CE. Some committed suicide. Others stayed loyal and were spared. This revolt started when Bato, a chieftain of the Daesitiates, an Illyrian tribe that lived in the territory of today's central Bosnia, led a group of Illyrian auxiliaries that had been summoned to fight with the Romans against the Marcomanni to attack the Romans instead. Because of initial victories many other Illyrian tribes joined the revolt. I read The Great Illyrian Revolt: Rome's Forgotten War in the Balkans, AD 6–9 by Jason Abdale about the revolt but the author is rather tongue-in-cheek and he uses a lot of unreliable and even irrelevant Greek quotes to fill out the book. Still there was interesting and informative content.
"In the aftermath (of the Bellum Batonianum), some Delmataean communities were relocated in the northern Sandzak region and others were resettled in parts of Carinthia to provide labor for the Roman mines." - Dalmatae
Following the "pacification", many Illyrians were either pressed into Roman military service or found it a lucrative career. Even after the fall of the western Roman Empire, the Byzantines continued to recruit in Illyria.
Later, raids from Slavic tribes could have displaced men living in the western Balkans. I don't know where the slaves would have been taken but it seems possible that some were taken back toward eastern Europe. This could represent one possible vector for J2b-Z631 to have become integrated into what are now Slavic countries outside of the western Balkans.
Later, when the Slavs migrated en masse into the Balkans, there may have been refugees who decided to look for opportunities elsewhere if the Slavs took the best land. So it is possible that the present day distribution of J-FT117099 was the result of their ancestors having been pushed to the south from an original homeland further north.
How J2b-FT117099 sheds light on J2b-Z631 origin
If J2b-FT117099 originated 600 BCE in the western Balkans and the closest related Bronze Age ancient sample is also from the western Balkans, the aforementioned 1200 BCE Gudnja Cave, Croatia I26726, it makes the most sense that J2b-FT117099 represents western Balkan geographic continuity that ultimately dates back to J-Z615 with TMRCA 3000 BCE who arrived in the Balkans either at that time or no later than 1900 BCE.
Two more closely related, though more recent, ancient samples are J2b-Z631 sample R116 from Via Salaria Necropolis in Rome 100-200 CE and three J2b-Z1043 samples (likely related) from a Roman military cemetery in Timacum Minus, now Ravna, Serbia dating to 395 CE.
All ancient J2b-L283 samples can be seen on the J2b-L283 ancient DNA map created by Flor Veseli.
We will figure it out
Despite the difficulties we are presented with, we have a good chance of eventually figuring out where some of the Iron Age lineages of J2b-Z631 had originally been living.
More ancient samples are going to be discovered and published. We are just too prolific not to show up in future studies. Perhaps the absence of our prolific J2b-Z631 line from the recently published ancient samples from the Adriatic coast from Slovenia to southern Croatia could be indicative that we were not from the Adriatic coast, but further inland...
While very little may be known of the specific Illyrian tribes inhabiting areas of the western Balkans, because they didn't write anything themselves and you cannot trust everything that Greeks wrote, I think we'll soon be able to place subclades as having formed in various subregions of the western Balkans. In some cases this may correspond to known Iron Age tribal polities.
You can help advance the research into J2b-Z631 origins by donating to my fund to purchase WGS400 / Big Y upgrades and YFull analysis for men that I have identified as likely to advance this research based on their STR/SNP results and male line origins.
Mention J2b-Z631 in the comment.