Piat an isolate?

I have been wondering what the evidence is for Piat being an isolate.
I imagine that there is tons of superstrate influence, and that native
linguistic material is rather reduced. Further, I'd have thought that
there are an awful lot of candidates for a genetic relationship to be
ruled out before we can take "seems to be an isolate" to mean
more than "noone has done the research yet" or "noone who
publishes in English has done the research yet". Also, how much
do we know of the origins of the Piat? Do we know when they
entered Central Europe, and where they came from?

On a slightly different topic, do we know anything of how the Piat
fit into the larger society of the nations that they live in? Are they
peasants? Farmers and pastoralists in areas too meagre for
anyone else to bother farming? Disenfranchised latecomers
periodically persecuted and barely surviving as an ethnos past
1945?

 --And.