Mbira is an instrument associated with the Shona people of Zimbabwe. It is a keyed instrument, sometimes referred to as a thumb piano, that contains between 20 and 50 tuned metal strips, prongs, or keys attached to a resonating chamber. They are commonly tuned to a heptatonic scale, although one of the four types of mbira is tuned to a hexatonic scale. Religiously, these instruments are very important in ceremonies dealing with spiritual possession and political involvement & protest. Ceremonial music often begins at sundown on Saturday and continues through to the early morning hours of Sunday. Mbira thumb-piano music became adapted to the electric guitar during the 1970s and 1980s. The guitar music, combined with the beseeching melodies and rough rhythms of the shona, became associated with the beer-filled nights of anti-colonial protests. Chimurenga, which means struggle, is the music and dance style developed by Thomas Mapfumo from the mbira rhythms and indigenous musical roots of Zimbabwe. Mapfumo protested against the racist government and re-introduced the music of Zimbabwe to her people.