The Sona drawings, plural of Lusona, were part of the tradition of the Tchokwe People. It is known in eastern Angola and close to the borders of Zambia and Congo. The drawings were made in the sand only by men, as a way to tell a story or show the reality of them (with representations of daily, nature, animals and people). It was part of the boys' rite of passage to adulthood to learn to draw Sona and tell stories.
Mathematical concepts such as Combinatorial Analysis, Minimum Common Multiple and Maximum Common Divisor were used instinctively, since the Tchokwe people had no knowledge of the formulas and math of the graphs. First, the soil was cleaned and flattened with the hand, and with the fingertips it was drawn an grid of points with carefully proportional spaces. Subsequently, the narrator traced lines - straight and curves with a 45 degree inclination - around the points without taking his fingers from the sand until finishing the drawing.
GERDES, Paulus (2014),"Geometria Sona de Angola - Volume 2: Explorações educacionais e matemáticas de desenhos africanos na areia", Centro de Investigação Etnomatemática & ISTEG, Boane