The bandoneon seems inseparable from Argentine tango, yet the instrument was developed in nineteenth-century Europe and arrived in Buenos Aires later. Early tango groups commonly used combinations of violin, guitar, flute and piano. The bandoneon gradually entered these ensembles and became increasingly central as quartets and, from around 1910, the larger orquesta típica developed. The standard tango orchestra eventually brought bandoneons together with violins, piano and double bass.
I like how completely a migrating instrument can become identified with a music that did not invent it. The bandoneon arrived with its own mechanical construction and tonal possibilities, but musicians in Buenos Aires gave it another cultural life. Its ability to sustain, swell and reshape a note suited tango so well that the imported instrument eventually sounded local.
Musical identity often works like this. Cultures do not necessarily become distinctive by avoiding outside influences. Sometimes they become distinctive through what they do with something that arrived from elsewhere.
https://buenosaires.gob.ar/gcaba_historico/tango/orquesta-tipica