Of all the tribes in the Javari (Yavari) Valley of Brazil and Peru, Mariwin is only practiced by the Matis tribe.  The Matsés tribe practices a related ceremony called "Comoc" in which hooded beings appear that sing instead of talk.  They do not, however, wear ceramic masks as do the Matis during the Mariwin Ceremony.  The bright red color of the masks is from an annatto dye obtained from the fruit of  the Bixa orellana tree.