Tribal warfare is a common among the tribes of Papua New Guinea. They fight over three things: land, pigs and women - in that order. To be regarded as important, men need plenty of each: land for farming, pigs as a measure of wealth and a number of wives to tend to land and livestock.
Many indigenous groups of Papua New Guinea in the isolated mountainous interior have little contact with one another, let alone with the outside world, and live within a non-monetarised economy dependent on subsistence agriculture.
The mudmen could not cover their faces with mud because the people of Papua New Guinea thought that the mud from the Asaro river was poisonous. So instead of covering their faces with this alleged poison, they made masks from pebbles that they heated and water from the waterfall, with unusual designs such as long or very short ears either going down to the chin or sticking up at the top, long joined eyebrows attached to the top of the ears, horns and sideways mouths.