The only contact with the foreign Trailmen is through trade conducted once a year in silence and by sign language, since the isolated tribes are thought to have no common language.

NPR: From New York State: Science, Fiction and Bar Yarns

There are numerous hiking opportunities in the park, including the ascent of the 2, 364m-high Mount Iglit, and the loincloth-wearing indigenous Mangyan people who populate Mindoro's virtually impenetrable interior offer serious explorers a chance to visit one of Southeast Asia's most isolated tribes.

BBC: The undiscovered jewel of the Philippines