There is a lot of mystery related to this language – it has no relation to any other language in the world.
http://www.bbc.com/…/20170719-the-mysterious-origins-of-eur… – Comparison from BBC of Basque & surrounding European languages. Basque is very distinct.

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BBC.COM
When Gen Francisco Franco banned the use of the ancient Euskara language, residents of the Basque Country fought to keep it alive.