***Stunning heavy psychedelic rock from 1971 by three virtually unknown Mexican groups! Four tracks from the amazing hard-driving and funky EP by LOS PAPOS (released by Orfeon in 1971); four previously unreleased tracks by LOS FREE MINDS, and the only two extant songs by POLVO, an amazing heavy psychedelic rock group from Nuevo Laredo. Los Free Minds was a Mexican psychedelic rock trio, formed in 1970 by JORGE AGUILLERA (guitar, vocals), JESUS PEREZ [El Jali] and drummer ERNESTO ONTIVEROS. Although invited, the band could not take part in the legendary rock event the Festival de Avándaro held in September 1971; after that, rock music was banned for many years in Mexico, which killed the careers of many bands. In the same year, shortly before their disbandment, Los Free Minds recorded an LP for Orfeón, but only four tracks from it were released as an EP, leaving tracks in the can which debut here. This limited edition LP comes with an insert.