Trying to find the exact "tribal" group may be stretching things a little, I think it is pretty sound to say it is a ritual piece for the Congo which narrows it down to an area roughly the size of western Europe. Try the search facility here, you should find other ritual spears, I have post a few of mine here
. I think if this is your first dip in the waters then you have done very well. I think you are hooked. Tim