RE: leaving EY to learn Torah. The Sifri reference by Ytz loosely tranlated by yours truly
A maaseh with Rabbi Yehuda ben Beseira, Rabbi Masiah ben Harash, Rabbi Hanania bar Ahi,Rabbi Yehoshua and Rabbi Yehonasan, who were going to hutz laaretz (reason unspecified) When they reached Paltom, they remembered Erez Yisrael and lifted their eyes, and they wept. They read (recalled) the mikra “that you shall inherit them, and dwell in their land (devarim 19) that dwelling in EY is weighted against all the mitzvot. They reversed and went back to their place.
A maaseh with Rabbi Elazar ben Shamua and Rabbi Yohanan Hasandlar who were going to learn Torah with Rabi Yehuda ben Beseira. They reached Tzidon, remembered Eretz Yisrael, wept, and returned home.]
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It is notable that in the second tale, Rabbi Yehuda ben Beseira had obviously overcome his original reticence to leave, as he was one of the travelers in the first tale. The point remains, that there were those who could not leave EY even for talmud torah, This was the dor shel shmad, they had lost sovereignty to the Romans, and it was for the survival of Torah that some went chu’l to set up Torah centers out of the reach of the Romans. Rabbi Hananya be Ahi is also mentioned as setting up in chu’l, a team was sent to him to put him in nidui for setting years and iburim in chu’l