Rav Yitzchak bar Chananin [(and in Yuchsin in the order of tradition from the Rama"n, bar Rav Chiya)] became head of the yeshiva in Pumbedita from year 4587 for 12 years [(and see above year 4569 where Rash"b wrote year 1140 of the Seleucid era, so it is year 4588)].