Trikiti

The trikiti (standard Basque, pronounced [tɾiˈkiti]), trikitixa (dialectal Basque, pronounced [tɾiˈkitiʃa]) or eskusoinu txiki ("little hand-sound") is a two-row Basque diatonic button accordion with right-hand rows keyed a fifth apart and twelve unisonoric bass buttons. The onomatopoeia trikiti, apparently stemming from the sound emitted by the tambourine, originally referred to a traditional Basque ensemble, made up of the instrument which now bears the name as well as alboka, txistu and other instruments.

Probably introduced by French or Italian immigrants coming from the Alps, the trikiti's first written evidence is attested late in the 19th century, exactly in 1889, when diatonic accordion was used for music in a popular pilgrimage festivity of Urkiola (Biscay). In 1890, a trikiti appears in a picture taken in Altsasu (Navarre), a railway junction. Therefore, some point to the instrument's import to the Basque Country from Italy through the port of Bilbao, while other sources suggest that this kind of diatonic accordion was brought in by Italian or French railway workers from the Alps. The diatonic button accordion itself was devised in Vienna in 1829, expanding thereafter all over Europe.

The pair of diatonic button accordion along with tambourine gradually grew in popularity and was adopted to perform in local and popular festivities, where the young danced to its tunes (fandangos, arin-arin etc.), despite the Catholic Church's resistance, who dubbed it "hell's bellows" on the grounds that its dance-inciting and lively music would lead Basque youths into temptation.

...
Wikipedia