In Jilib in the 1960s "diger" was a general term for all kinds of beans, which included American beans, adzukis, lentils and black-eyed peas. "Canbulo" was common and usual farmers' food. It was beans of any kind or a combination, boiled with dry maize and eaten dry so it could be picked up in the fingers. The combination forms a protein for people in the Gosha, unable to raise much, or any, livestock because of tsetse. I liked it.
I had a meat grinder to make hamburger, which, added to beans, tomatoes, basal, toon and basbaas, made chile, one of my staples.
It's also most famously eaten with roasted coffee beans and is referred to as bun iyo (c)ambuulo. As far as I'm aware, coffee doesn't grow in the south/wasn't historically grown in the south. If this is a fact, then can we say it was imported from Ethiopia?
I never saw any bun, I think because Jilib is so far from the source, which I agree was likely Ethiopia. I did see the whole dry beans, but they were rare and I never saw any in the farming villages. What I saw in Jilib was pounded whole in a moi with dry basbaas to a fine powder, boiled with water and served with much sugar in something like a shotglass. That stuff would knock your socks off right now! Qahwe (?)
It was not nearly as common as shah, and I dont think had any special connection to cambuulo.