Gerard Lucotte and Pierre Smets in Human Biology (vol 71, Dece 1999, pp989-993) studied the DNA of 38 unrelated Falasha males living in Israel and 104 Ethiopians living in regions located north of Addis Ababa and concluded that "the distinctiveness of the Y-chromosome haplotype distribution of Falasha Jews from conventional Jewish populations and their relatively greater similarity in haplotype profile to non-Jewish Ethiopians are consistent with the view that the Falasha people descended from ancient inhabitants of Ethiopia who converted to Judaism."
Scholars are divided on when and how Judaism was adopted by the Falasha: whether from Jews living in Yemen, from the Jewish community in southern Egypt (Elephantine), or even from a permanent Jewish community in Ethiopia implied in Isaiah 11:11 (ca 740 BCE)
The utter isolation of the Falasha was reported by an explorer James Bruce, who published his Travels to Discover the Source of the Nile in Edinburgh in 1790. But 1860 before a converted Jew actually went to Ethiopia to convert the Falasha.