You are most likely referring to the Cusqueña Beer festival. Cusqueña is a very popular pruvian beer with its headquartes in Cuzco city. Every year, usualy in July they have a big festival, but it is mostly jsut a big concert with local and popular south american bands. Not really a folkloric festival.
hope this helps,
Richard Leon
www.peruforless.com www.peruluxurytravel.com www.argentinaforless.com