His closest colleagues wereRav Ashi andAmemar. The three of them are described together in their studies, meals, and visits to the court ofYazdegerd I.[3]
He headed theYeshiva ofPumbedita, and according to the book "Seder Tannaim ve-Amoraim", previous toRav Aha b. Rava. In theIggeret RavSherira Gaon (French version), he is not mentioned as a head of aYeshiva, but in later sources he is noted as Mar Zutra, Head of a Yeshiva.