Pre-Axumite Stamps, Ethiopia
Well, I don't know whether ancient Ethiopians used these objects as stamps. But they all have handles on the back. They appear to be perfectly suited to stamping designs on fabric, plaster, etc.
To test this theory, I suppose one would need to search the literature (!!) or review collections for corresponding impressions on materials from archaeological sites.
Update: At the "Matara" Web site (which has since been shut down), these objects were described as "bronze identity stamps;" each figure encloses letters in the Da'amat language that form a person's name.
In the collection of the National Museum, Addis Ababa, Ethiopia. Taken without flash.
I've complied with restrictions on the use of flash, and taken photos only when permitted by the museum.