The Veneti lived in Paphlagonia. It is possible that it was the Veneti that before the Trojan War spread as “Arians” into India. This would explain the Mount Demawend, R1a in Afghanistan and the various “Venetic” names in India.
We can assume that the Veneti spoke a language akin to Slavic (names of places in Anatolia that include Prusa suggest that). But it is possible that they got Slavicized.
At some point after the Trojan War, they went over the Ister and ended up spreading their “Slavic” language (or adopting the Slavic of the autochtones they encountered) all the way up to the Adriatic. It is for this reason that the Slovene city of Ljubljana has Jason feature in its founding myth. It’s likely that Jason was in fact a Venetic fertility God that found His way into Greek myth.
The Veneti went further ending up in today’s Poland as well as Eastern Germany and Noricum/Vindelicia, today’s northern France and southern portions of Italy and even northern Spain/Portugal. And they may have reached present day Denmark and southern Sweden and perhaps even Britain.
The Trojan War has been dated to the 13th or 12th century BC. It is curious that the recently discovered remains of an ancient battle at Tollensee have been both dated to approximately 1250 BC and said to have contained dNA similar to that of present day Poles/Scandinavians but also southern Europeans. A tempting construct would see these as the “locals” and the “Venetic” arrivals.
It is possible that at this point Slavic was carved out of Baltic with the former a “Venetic” language or a mixture of Venetic and Baltic. The Veneti became Slavs – from Trieste through Noricum, possibly Suevia and up to the Baltic. The remaining Balts stayed Balts now designated Aestii.