Rav Avraham bar Sherira, brother of Rav Avumai, became head of the yeshiva in Pumbedita from year 4575 for three years [(Tzemach David), see above year 4569 in the name of Rash"b for 12 years. It appears this is an error, for he himself wrote afterwards: after him Rav Yosef ruled in year 4577. And according to this, what the Aruch wrote that it was year 4588 is not this one who died in year 4577. And see in the Aruch, entry Sach: It is said that Mar Avraham Gaon was in year 1140 of the Seleucid era (which is year 4588), he was familiar with the language of the palm trees, etc.

Perhaps this is him].