Modern protest music was born in Argentina during the Perón years in early 50s for various, domestic reasons. The "Nueva Canción" era, with folkloric and Pampa music as it's base, marked the end of the Classic Tango Era of the 30's and 40's in Argentine popular music. Nueva Canción quickly spread to Chile (Victor Jara, etc), where it really took off. From Argentina and Chile it spread to the rest of Latin America, including Cuba of course, where it's political tones gained their greatest strength. Protest Music then spread to the US in the 60's and eventually to the rest of the world.
Nueva Cancion and Mexican or Cuban Boleros dominated the 50's and early 60's in Argentina. In turn they declined late in the 60's as the 'sunny' pop of Palito Ortega, Club del Clan, and the rise of Argentine Rock revolutionized Latin American youth music, and early Adult Contemporary pop began dominating the charts.
I think Protest Music had it's 'era', certainly in Argentina at least. While I don't mind groups that mix a bit of politics in their lyrics, I start vearing away from them if their politics begin to outshine their sound.
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