Question over Ethiopian Jews?

Does anybody know where the Beta Israel originate? I know they didn't have knowledge of the Talmud so they must have been practicing jews for at least 2,000 years which means they pre-date the rise of Christianity in Ethiopia (which puts down the theory that they are Christian converts). DNA test say they aren't related to other Jewish populations because they don't possess two of the haplotypes, but they are related to Yemenite jews so how reliable were those DNA test (did they test a large enough sample of the Beta Israel community). I know they believe they are from the tribe of Dan, but would Danites have different genetic markers from individuals from the tribe of Judah or other Israelite tribes? If anybody has any answers on their origin it would be greatly appreciated.