Ukban ben Nehmiah was a Jewish Amora sage of the third generation, who, according to Joseph ben Ḥama, who was a contrite sinner. The Seder 'Olam Zuá¹Âa, too, in the list of the exilarchs, mentions an exilarch called "Ukban d'Zuzita" who was buried in Israel. According to the geonim áºÂemaḥ and Saadia, Ukban, when he was young, was wont to curl his hair, his surname "de-áºÂuáºÂita" being derived from that habit. Another interpretation is that fire would flash out from his áºÂiáºÂit, so that nobody could stand near him.
As to the nature of Ukban's sins and repentance Rabbi Aḥai of Shabḥa, in his "She'eltot" (sections "Wa'era" and "Ki Tissa"), tells almost the same story as Rashi, of a man who was called "Nathan de-áºÂuáºÂita," but without mentioning either that he was likewise called "'Ukban" or that he was an exilarch. Further, this story is related by Nissim ben Jacob in his "Ma'aseh Nissim," at great length, Nathan being placed in the time of AkibaâÂÂthat is, not later than the first third of the second century.
It may therefore be assumed either that there were two Nathan de-áºÂuáºÂitas, the second being identical with the exilarch Ukban b. Nehemiah, or that Joseph b. Ḥama must be understood as comparing Ukban, in his repentance, to Nathan de-áºÂuáºÂita, who was much earlier and, perhaps, was not an exilarch. It is true that in the Seder 'Olam Zuá¹Âa it is clearly affirmed that Nathan I was called also "Ukban"; but in other details the three recensions of that work disagree with Joseph ben Hama, in that they leave it to be supposed that Nathan de-áºÂuáºÂita was the son of Anan and not of Nehemiah, and that they represent him as the father of Huna the exilarch, who lived in the time of Judah ha-Nasi I. The Seder 'Olam Zuá¹Âa has in its list three exilarchs called "Nathan," the second being the grandson of the first, and the third the son of Abba ben Huna and father of Mar Zuá¹Âra; it is the chronology of Nathan III that coincides with that of another Ukban.
It may be added that Rashi (to Sanh. l.c.) confuses Nathan de-áºÂuáºÂita 'Ukban with Mar Ukba, "ab bet din" in the time of Samuel, which time coincides with that of Nathan II. Lazarus (in the list of exilarchs in Brüll's "Jahrb." vol. x.) supposes that Nathan I reigned from about 260 to about 270, and Nathan II from 370 to about 400.