John Thomas Koch[1] FLSW (born 1953) is an American academic, historian, and linguist who specializes in Celtic studies, especially prehistory, and the early Middle Ages.
[5] In 2008, Koch gave the O'Donnell Lecture at Aberystwyth University titled People called Keltoi, the La Tène Style, and ancient Celtic languages: the threefold Celts in the light of geography.
From there (in this scenario) they spread east to South Central Europe, including the Pannonian Basin, where early forms of the Proto-Italic already would have been developing independently from Proto-Indo-European.
[9] This language or languages also influenced early Pre-Proto-Germanic, the direct ancestor of Proto-Germanic, but not yet a fully Germanic proto-language, (possibly located in the southern coast of the Baltic Sea or other place of North Central Europe) and contributed to its rifting from the Balto-Slavic/Indo-Iranian dialect continuum (in the western Corded Ware Culture area).
[10] This idea, the subject of three edited volumes in a series by Koch and Barry Cunliffe called Celtic from the West (2012–2016), is controversial.