**Rabbi Yochanan** became Rosh Yeshiva in Eretz Yisrael after Rabbi Chanina, around year 3990. He was Rosh Yeshiva in Eretz Yisrael for 80 years. Rabbi Yochanan died in the year 39 to the fourth millennium [i.e., 4039]. So wrote the Ra'avad as brought in Yuchsin, and so wrote the Rashba in Yuchsin: 596 to documents [i.e., Seleucid era] Rabbi Yochanan passed away.

But there is confusion in this calculation because Rabbi Yochanan was Rosh Yeshiva in Eretz Yisrael for 80 years, and according to...