Edited from Wikipedia:
"Liceu Vieira Dias, Domingos Van-Dúnem, Mário da Silva Araújo, Manuel dos Passos and Nino Ndongo created around 1947 the Ngola Ritmos band, in order to assert their Angolan identity. Ngola Ritmos created a style that would inspire generations of musicians. The lead guitar introduced the theme and often intervened in counterpoint to the voice. The second guitar ensured the rhythmic frame, the bass guitar (six-stringed at the time) marked the beat, almost like a percussion, while the drum and dikanza (scraped instrument) backed up the ensemble. Singing was inspired by popular traditions, the chorus answering the lead voice. While such songs as Mbiri Mbiri, Kolonial, Palamé or Muxima have been covered by numerous singers, recordings by Ngola Ritmos are very rare. Most of the members of Ngola Ritmos were nationalist militants; Liceu, a founding member of the MLPA liberation movement and Amadeu Amorim were arrested in 1959 and deported to the Tarrafal prison in Cape Verde, to return only ten years later. Nevertheless, the band lasted until the late sixties."