Ukvan bar Nechemiah the Exilarch (article preview)

On Bava Batra 55a, Rabba (bar Nachmani) relates a set of three teachings which Ukvan bar Nechemiah, the Exilarch, told him in Shmuel’s name. The first, most famous one, is דִּינָא דְמַלְכוּתָא דִּינָא, there’s halachic validity granted to the law of the land. The second is that Persian sharecropping is up to forty years (since chazaka in Persia was after forty years of use). The third is that there’s validity to a land sale by tax officials who sold it to pay the land tax. Presumably, the second and third are dependent upon the first teaching. 

What do we know about Ukvan bar Nechemiah, the Exilarch? At first glance, very little. His only other occurrence is in Shabbat 56b. There, Rav said: There’s no greater ba’al teshuva than (King) Yoshiyahu in his generation, and there’s one in our (first Amoraic) generation. The gemara explains this is second-generation Rav Yirmeyah bar Abba I’s father, Abba; or alternatively in another internal variant, Abba’s brother Acha. Then, third-generation Amora, Rav Yosef, said: There’s another great ba’al teshuva in our generation, namely Ukvan bar Nechemiah the exilarch, also known as Natan Detzutzita. Rav Yosef elaborated that once, he was dozing at a Pirka, a lecture delivered on a Festival, and saw in a dream that an angel stretched out his hands and received him (thus indicating that Natan’s repentance had been accepted).

I’d fix Ukvan bar Nechemiah in the second and early third Amoraic generation. I assume that mishum indicates a direct communication from a relatively early Amora, Shmuel, rather than how some take it, as indicating an indirect tradition. I discussed this in greater detail in an earlier Jewish Link article, “On Behalf Of” (September 1, 2022). He has to be contemporary enough to Rav Yosef to describe him (in Shabbat) as בְּדוֹרֵנוּ. Further, third-generation Rabba bar Nachmani cited him as an intermediate to Shmuel.

Now, Masoret HaShas notes that the girsa of the Rif and Rosh is that fourth-generation Rava, rather than Rabba, heard this report from Ukvan bar Nechemiah the Exilarch. It is Rabba in the Vilna, Venice, and Pisaro printings, as well as the Florence 8-9, Oxford 369, and Vatican 115b manuscripts. However, the Hamburg 165, Munich 95, Paris 1337, and Escorial manuscripts all have Rava.

Paris 1337 manuscript, with Rava

I can see the argument for Rava. After all,