Son cubano is a genre of music and dance that originated in the highlands of eastern Cuba during the late 19th century. It is a syncretic genre that blends elements of Spanish and African origin. Among its fundamental Hispanic components are the vocal style, lyrical metre and the primacy of the tres, derived from the Spanish guitar. On the other hand, its characteristic clave rhythm, call and response structure and percussion section (bongo, maracas, etc.) are all rooted in traditions of Bantu origin. Around 1909 the son reached Havana, where the first recordings were made in 1917. This marked the start of its expansion throughout the island, becoming Cuba's most popular and influential genre. While early groups had between three and five members, during the 1920s the sexteto (sextet) became the genre's primary format. By the 1930s, many bands had incorporated a trumpet, becoming septetos, and in the 1940s a larger type of ensemble featuring congas and piano became the norm: the conjunto. Besides, the son became one of the main ingredients in the jam sessions known as descargas that flourished during the 1950s. The international presence of the son can be traced back to the 1930s when many bands toured Europe and North America, leading to ballroom adaptations of the genre such as the American rhumba. Similarly, radio broadcasts of son became popular in West Africa and the Congos, leading to the development of hybrid genres such as Congolese rumba. In the 1960s, New York's music scene prompted the rapid success of salsa, a combination of son and other Latin American styles primarily recorded by Puerto Ricans. While salsa achieved international popularity during the second half of the 20th century, in Cuba son evolved into other styles such as songo and timba, the latter of which is sometimes known as "Cuban salsa".