"Tangra" is a popular and loved Bulgarian band. For the Green Rock Fest Tangra will be composed of the following musicians: Konstantin Markov, Stanislav Sanev - Stanley, Yordan Ganchev and the guest musicians Ivo Chalakov and Stefan Popov from "Gravity Co". "Tangra" comes with a new energy and a special concert program in which they will present their biggest and most beloved hits since the band's creation to this day. The band was created by Konstantin Markov and Alexander Petrunov (Sasho Bracelet) in 1976 and existed until 1990. Many of their fans believe that it ceased to exist in 1986, but it actually happened four years later, because between 1986 and 1990 the musicians played in Scandinavian countries.

Well known Bulgarian musicians Tsvetan Vladovski - Chocho, Stanislav Sanev - Stanley, Vali Kavaldjiev, Lyudmil Hristov, Iliya Karayanev (Lido Stonsa), Tenko Slavov, Danny Ganchev, Valeri Milovanski and many others have been members of the band over the years. In 2016, "Tangra" re-emerges from Constantine Markov, Stanislav Sanev and Yordan Ganchev.