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I think they've got no clue about languages spoken at either site, and it will probably remain that way. Imagine what it would take -- there would have to be a body of inscriptions contemporary with a site; a bilingual text, both unreadable, but one a later successor tongue, which also has some sort of body of inscriptions at some site or sites; then another bilingual inscription with a third successor; and this sequence would have to repeat until the newer language on the bilingual were one someone knows how to read.
Here's one of my favorite clippings for reprise -- there are short inscriptions in the European cave paintings:
In her Plato Prehistorian: 10,000 to 5000 B.C. Myth, Religion, Archaeology, Mary Settegast reproduces a table which shows four runic character sets; a is Upper Paleolithic (found among the cave paintings), b is Indus Valley script, c is Greek (western branch), and d is the Scandinavian runic alphabet.