"The Boa originated west of the Zaire River. During the 18th century, they migrated eastward toward the Mbomu River. In the 19th century they were attacked by Azande invaders but successfully resisted Azande domination. The Boa were known as excellent warriors, but after 1910 Christian missionaries succeeded in destroying the last remnants of tribal unity (Vansina 1966). The masks of the Boa are extremely rare and have been widely copied.
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The use and function of the masks are unknown, but they are usually described as war masks that belonged to secret societies or warrior's societies. They have also been described as disguises for hunting monkeys, although their dramatic forms could hardly have inspired confidence in such animals."
(source = The Stanley Collection of African Art at The University of Iowa Museum of Art, WWW site, 1999)
"The Boa tribe comprises 200,000 savanna-dwelling people living in the northern part of the Democratic Republic of the Congo. Each village is headed by a chief from the most prestigious clan. The Boa are mainly farmers and are in frequent contact with Mangbetu and Zande. The Boa are known principally for their masks, believed to be used in war-related ceremonies, to enhance the warrior's courage or to celebrate victories. These masks have set apart, prominent, round ears, suggesting alertness, and are covered alternately with dark and light pigments. The Boa also carve statues with apotropaic functions. They also produce harps with human heads carved at the neck."
(source = zyama.com, 2003)