batak knives?

[Green]

I bought these knives some years back which are supposed to be from the Batak tribes of Sumatera. The blades are plain but the scabbards were decorated quite nicely and made of deer antler.

I wonder what these knives are for? are they just tourist traps or used in some ways culturally? Looked quite old but I'm not sure, may be early or mid 20th century. Hope someone(s) can explain.