Yalli, traditional group dances, are dance expressions based exclusively on collective performances. Typically, yalli are performed in a circle, chain or line, and involve elements of games, pantomime (bird or other animal imitations), physical exercises and movements. The community of the yalli dances consists of practising dancers, who enact the dances either spontaneously or in a planned manner at various festivities and celebrations. Some variants of yalli bear a song-like character and are practised by both women and men, while others are practised by men only and imitate pastoralist games with some elements of butting animals. Until the mid-twentieth century, yalli were widely practised but several factors have impacted the transmission of the practice thereafter. They include a gradual loss of social functions for certain types of yalli, a preference for staged performances, external factors such as labour migration and the economic crises of the late 1980s and early 1990s, a shift from informal to formal transmission, and a drastic simplification of the dances, which has entailed a loss of diversity.