My research relies on the study of a class of sowing games largely unknown in Europe and, more broadly, in almost all the Northern Hemisphere: the solo. This chapter focuses on an ethnography carried out in my fieldwork: the part of the southwest of the Indian Ocean where these games are very common. Through interviews with inhabitants of the concerned countries (Tanzania and especially the island of Zanzibar, the Comoros archipelago, Madagascar and Mozambique) and video sequences that I filmed in Madagascar and Mayotte, I deliver several analyses and models. First, all the solos derive from the bao of Zanzibar, -the most complex type-, following the trade routes of the dhows in the region, to give the mraha of Mayotte, the various katro of Madagascar, and other solo. Secondly, the seemingly illegal and incomprehensible moves of expert players can be understood by their desire to optimize seeds freight and loading / unloading operations. Thirdly, the extremely fast moves of these same expert players can be modeled by the knowledge of a set of simple graphs, the vertices of which are the successive connected configurations of seeds. Finally, as a tutor for teachers, I give some ideas of a didactic exploitation of the sowing games when teaching mathematics from nursery school to high school.