Wooden containers were carved by Tutsi men and often mimic the shape of their baskets, which are made by women. This particular example has a more fluid, curvilinear design as opposed to the more typical geometric zig-zag patterns. It may be a regional variation associated with the Tutsi of Uganda, according to Margaret Trowell in Tribal Crafts of Uganda where a similar piece is illustrated on page 114.
Tribal Crafts of Uganda. Margaret Trowell, pp114