Well, heres Wiki with a brief article on the Mangyan.
Mangyan - Wikipedia, the free encyclopedia
It says that some that live in proximity to the Filipinos do sell some produce.
These Mangyan are waiting for a bus! No women though.
They even have their own 'Cultural Centre' now. Just maybe, things are getting better for them. It's located in Calapan, a market town not far from touristy Puerto galera.
Mangyan Heritage Center