Chile Music Cinderella - Any Information?

Does anyone know anything about this Cinderella or the music 'event' it seems to advertise/commemorate?

Primer Congreso de Musicos or First Congress of Musicians in English.

The Congress of Musicians involved the cognitive studies of the music and cultures in Latin American; this was largely done, in part, through ethnomusicological narratives.

The First Congress of Musicians was held in Santiago from 1 to 5 July, 1940.
It was organised by the Trade Union Professional Orchestras of Santiago, under the direction of its president/director Pablo Garrido Vargas (1905-1982) and with the participation of musician's delegations from all regions of the country.

In those years the orchestras and musician's band were numerous, and the objetives of the congress were join musicians to negotiate better, as an national association, against the recording studios, dance halls, radio's auditoriums, etc.

Pablo Garrido, as well as trade union leader and composer, was one of those who spread Jazz music in Chile and formed one of the first local Jazz bands.
He was also the first musician to introduced the music of George Gershwin here

There is a story behind every stamp, thank you.

Nice work Jorge