Some early morning googling led me to an interesting wikilink on the hypotheses on connections of Basque with other languages.
And this, from another site:
Early Basque-language publications were scarce. The first-known complete work in Euskara was a book of poetry produced by a Behe Naforroan cleric, Bernat D’Etchepare. His 1545 publication was printed and distributed in Bordeaux.
Which Basque words, if any, have found their way into English?