The spine markings are identical to those found on many Montagnard dha, and the blade engravings (if not the inlay--those are quite unusual in my experience) similar to this dha of Mark's:
Northern Thai seems more and more likely for that one.
Montagnard dha spine markings:
Similar spine markings seem to appear on weapons from a wide geographic area, from China to the north right down through most of SEA.