Mambo was developed as an offshoot of danzón, the national dance of Cuba, in the late 1930s by Orestes López and his brother Cachao, of Arcaño y sus Maravillas. They conceived a new form of danzón influenced by son cubano, with a faster, improvised final section, which allowed dancers to more freely express themselves, given that danzón had traditionally a very rigid structure. In the 1940s, Dámaso Pérez Prado transformed the mambo from the charanga into the big band format, and took it to Mexico and the United States, where it became a "dance craze".