The Shimon bar Yochai of the rabbinic sources is a documented second-century teacher, counted among the students of Rabbi Akiva who survived the persecutions following the Bar Kokhba revolt. He appears constantly in the Mishnah, the Tosefta and both Talmuds, usually in legal argument, and the positions credited to him are sharp, ascetic and unusually willing to reason from the purpose behind a law rather than from its letter.
The most famous story about him is told at Shabbat 33b. Having spoken against Rome, he flees with his son Elazar, and the two hide in a cave for thirteen years sustained by a carob tree and a spring, studying without interruption. When they emerge, the sight of ordinary people working the land is unbearable to them and everything they look at is consumed by fire, so a voice sends them back for a further year. The passage is a rabbinic parable about the cost of undivided study rather than a chronicle, but it fixed his reputation as the sage of withdrawal and hidden knowledge, and it is the seed from which the whole later legend grows.
His grave at Meron in the upper Galilee became a pilgrimage site, and the bonfires and gatherings held there on Lag BaOmer remain among the largest annual assemblies in Jewish life. No birth or death year is recorded for him anywhere in the rabbinic literature, which is interested in his rulings and his sayings and not in his biography. Every date offered for him is inference from the generation of teachers he is placed among.