There is a tendency to label every West African dagger as Mande. Not sure is this is always correct, but I do believe the group of daggers shown here is indeed Mande. This is still a very broad definition, similar to labeling something as Slavic or Turkic in a way, so it would be great if at some point we can do a little better.
The British Museum shows three similar daggers, all collected in the first half of the 19th century, one of which was collected in Guinea, one in Sierra Leone and the final one in the Bijagos islands.
https://www.britishmuseum.org/collec...1852-0930-35-a
https://www.britishmuseum.org/collec...ject/E_Af-5319
https://www.britishmuseum.org/collec...f1878-1101-521
Based on this, a distribution from what is today South Senegal to Sierra Leone is possible. It would be interesting to learn more about these knives.