1839, from Welsh Cymru "Wales," Cymry "the Welsh," plural of Cymro, probably from ancient combrox "compatriot," from British Celtic *kom-brogos, from collective prefix *kom- (see com-) + *brogos "district," from PIE *merg- "boundary, border" (see mark (n.1)). Compare Allobroges, name of a warlike people in Gallia Narbonensis, literally "those from another land."
