I found this dagger on a small Belgian auction site (yes, we have these,too

). The seller's description mentioned a handle made from bone. So I ended up buying this curious thing.
This morning, I received it and was very pleased with what I got. Only....I'm not sure what I've got. After examining the piece, I noticed that the round metal guard between the blade and the handle is a coin. On it I can read : Indochine - 1939. So I presume it has a Southeast Asian origin. Would it be that old ?
The blade is crudely forged, with the cutting edge on the curved side. It has a strong back, 3 mm thick.
The handle is made from some kind of animal bone with a good patina. Near the guard the handle is reinforced with a metal ring.
The wooden sheath consists of two pieces, held together with some rattan binding and a metal band near the top.
Measurments :
total length : 34 cm
length of blade : 20,5 cm
length of handle : 11 cm
I would appreciate your opions.