SPEAR for ID / Indonesia ? but where

[asomotif]

I bought this spear sad enough without any details except probably Indonesia.

Total length is 180 cms.
The wooden shaft is well patinated and has decorations on the top 20 cms and the bottom 20 cms.
Also there is a number, so it has been part of some kind of collection.

Any ideas to which island / tribe we can attribute this one ?

Thanks,
Willem