New to the forums here, thanks for the pdf.
One of the things that caught my eye was his analysis on the quality of weapons they produced.
"The blades are by no means of equal temper or perfection, but the smiths of the Tinguian-Kalinga border villages seldom turn out poor weapons, and as a result, their spears and head-axes have a wide distribution over northwestern Luzon."
Whats interesting is that regardless of how deep the interior is, you can still find quality produced weapons by people who are far from the coastal regions