Contemporary Bwa plank masks come from the Bobo Oule culture of Burkina Faso, and originated with the Nuna people in the south of the country. Their abstract designs played an important role in the development of Western art movements of the early 20th century. Bwa masks embody a range of protective spirits, from birds and monkeys to the sun itself. They are usually flat and painted with contrasting checkerboard patterns. The contrast between light and dark is often interpreted to represent the dichotomy of innocence and knowledge. The masks are worn at religious performances and celebrations.