Some kind of dha?

[PUFF]

Thanks for detailed pic. I just discussed with K. Bancha. The blade style was used during early(late C18th)-mid(late C19th) Rattanakosin. With this kind of spine, this one 's likely to be mid-Rattanakosin (as Ian mentioned, late C19th). The origin 's likely to be central Thailand because he found a similar example from NaKornSawan province. And the hamon 's likely to be differential harden rather than Sanmai