Rav Nachman bar Yitzchak belonged to the fifth generation of the Amoraim in Babylon. He lived about 1600 years ago. After Rava, the head of the Yeshivah in Mechoza died, the center of learning returned to Pumbeditha, and Rav Nachman was chosen as its head.

In his youth, Rav Nachman studied together with Rava, but he sat one row behind him. Later Rav Nachman studied under Rav Chisda. During the time when Rav Joseph bar Chiya was head of the Yeshivah of Pumbeditha and Rava conducted his own Yeshivah in Mechoza, Rav Nachman bar Yitzchak was the chief lecturer (Resh Kalah) under Rava, and he was already famous for his great learning and piety.

During the lifetime of Rabbi Nachman bar Yitzchak, the position of the Jews in the Holy Land was getting ever worse and the Yeshivoth there closed down. However, in Babylon the Yeshivoth continued to flourish. The Amoraim in Babylon began to write down the explanations and teachings which started from the time that the Mishnah was edited and completed by Rabbi Judah the Prince. Rab Nachman was one of the chief collectors of this body of learning in his time, which later was edited and completed into what is now known as the "Gemara." On one occasion, when Ravina engaged Rav Nachman in a discussion, and questioned him as to the authority of his decisions, Rav Nachman declared: "I am neither wise nor learned enough to express my own opinions, nor do I make a statement on the authority of a single scholar; but I teach only that which I heard studying at the Yeshivah, where I used to present the opinions of the Sages in good order, and it was taught this way in the Yeshivah." He used to be very careful to pass on the teachings and laws he had heard from his older colleagues and teachers in the exact wording of the original statement, as the correct version is very important in such matters.

Many are the teachings of Rav Nachman bar Yitzchak which are to be found in the Talmud, both in the field of Halachah and Agadah. One of his famous sayings about learning Torah is the following: "Why are the words of the Torah likened to a tree 'It is a tree of life to them that take fast hold of it' (Mishlei 3:18)? Because just as a small piece of wood lights a big one, so does the young student sharpen the wits of the older scholar."

His modesty may be seen from the fact that when Rava stated that "a little pride is becoming a scholar," Rav Nachman hastened to remark, "None of it, nor part of it!" He was a man of the highest qualities of character, and tried to teach his students to improve their character traits. He especially condemned anger and bad temper, saying that the best record of a man is spoiled by his bad temper.

Rav Nachman owed his great piety to his mother. We are told in the Talmud that an astrologer once told her that her son would grow up to be a thief. She then took especial great care that her son should always keep his head completely covered. She often reminded him: "My son, cover your head completely, so that you will fear G‑d, and always pray for his mercy, so that you should not be overcome by your evil impulses." This he did, and far from becoming a thief, he became one of the greatest Sages and teachers of his generation.