Well, how about the Welsh who settled the Missouri and gave rise to the Mandans or whomever?

Liland

PS But seriously, on what grounds are you proposing Celticness for Asturias or Asturians? The Iberians, or some Iberians, may have been Celtic (though some or all of them may also have been ancestral to the Basques, who are distinctly not Celtic (except on occasion by marriage). I think.