You may be right. One of the National Geographic articles was on an ancient Christian group in Ethiopia. They had pictures of tapestries and beautifully painted little Churches which were extremely old. I can't refer back to the articles because I only saved the artwork. I was impressed.
The TV documentary was definitely on a Jewish group though. I can't remember which country they were in but it wasn't Ethiopia. It was filmed within the last ten years.
There are Jews in Sudan also. At least some of the African Jews trace back to Jews who were imported, either by capture or by contract, to be guardians of the Nubian border area at a place called elephantine Island in the Nile River.