In a volume of unassuming size, Nora Chadwick introduces The Celts and their origins–her book was first published in 1971, then reprinted in 1997, then re-issued in 2001, London: The Folio Society with a recommended list of additional reading.
Ancient Celtic People’s of Europe: Eloquent, memory-trained, artistic speech, poets
Gaulish–Germany, Bohemia, Czech Republic
Two ideas that stayed with me:
1) Julius Caesar, alone, slaughtered about a million Celts.
2) Vikings transformed Ireland from a cattle-keeping country to a coastal one with towns, and people trading across borders.
Re-think what you have heard and read. Add this volume to your Summer reading list and fill your view with some new evidence. Your favorite American genealogist with British ancestry, Arlene Eakle http://arleneeakle.com
PS I have created a little outside nook, where I can read without being disturbed–under the trees in the shade on a wooden bench, with room for me and my books. So nice!