Rav Kahana of Pum-Nahara רב כהנא מפום נהרא

He presided over the court at Pum-Nahara and, by one reading, afterwards headed Pumbedita—the years of that headship are given as 395–412. He also delivered the funeral oration for Rav Zevid of Nehardea.

Caution is needed here: there are several Rabbi Kahanas in these generations, and the works of reference separate them differently. The Jewish Encyclopedia says of Ashi's teacher that he "afterward became president of the academy at Pumbedita", but gives no years; modern works give the years but assign them to a Kahana whom they call Ashi's cousin. We set the window by those years and name the disagreement.