 The unexpected success of their 1967 debut single "La balsa" was the kickstarter of Argentine rock, and pioneered Spanish-language rock.The group was started in the wake of an earlier band Los Gatos Salvajes, who had shared two the same members, in 1967.They recorded their first two singles ""Ayer Nomás"" and A-side ""La Balsa"", which turned into an unpredicted large scale hit in the Argentine winter of 67, selling over 200,000 copies, leading to their full-length debut later that year.