Rav Simona in Pumbedita and Rav Eina in Sura were heads of academies in the year 4279 [(see above 4263)]. And according to the Raavad, Rav Simona reigned for about 21 years. [And in Sefer HaKeritot, column 72: Rav Gada and Rav Simona are the end of Savora, end of quote. And it is wondrous that he did not mention Rav Gada.]