There are 55 masks in total, scattered through southern and northern Kyrat. Locations are indicated by a large blue circle on your map. As you enter the areas, you will begin to hear a hum that grows in intensity as you get closer to the mask. They can be either collected or destroyed. Near the masks, there will almost always be a body and a note left by The Goat. The notes usually tell how he sacrificed this certain person for Yalung or that he has been stalking them, but as you remove more and more masks and progress further north the notes get more cryptic. At several points in the notes he acknowledges that you're going around and removing his masks, stating the only reason he hasn't killed you is because "Yalung hasn't called your name".