TRUMBASH KNIFE WITH IVORY HILT, MANGBETU ?

[asomotif]

I picked up this Trumbash knife with an elefant ivory hilt.

The knife is probably in the Netherlands since 1938 but the seller had no further details. (thought it was a harvesting tool with bone handle)

Any idea on age and tribe ?
Mostly they are described to Mangbetu, but could this one be of a neigbouring tribe ?

Thanks in advance for any comments.

Best regards,
Willem