There were several sages by that name; one of them (in Tiberias, 3rd century CE) collated the Jerusalem Talmud. But the one whom you're asking about is probably the following:
Rabbi Yohanan ben Zakkai (1st century CE), disciple of Hillel, found favor in the eyes of the Roman leader Vespasian, for a reason explained in the Talmud (Gittin 56a-b), and was granted a request. He requested that the Romans (who had already begun the process of the Second Destruction) spare the town of Yavneh and its Torah-scholars. Vespasion acquiesced (Talmud, ibid), and Rabbi Yohanan gathered whatever Torah-sages he could, to Yavneh.
After the Destruction, it was these sages (Rabbi Eliezer, Rabbi Yehoshua, Rabbi Akiva and many others) who redeemed Jewish captives, distributed charity, and rebuilt whatever they could.
In matters of Torah, they recorded the laws of the Temple so that these wouldn't be forgotten, and redacted the details of such Mishna-tractates as Shekalim, Yoma, and Tamid. They finalized the text of the Haggadah shel Pesach (Passover Seder), composed prayers for the rebuilding of the Temple, and set in motion the process of redacting the entire Mishna, an effort which would be completed a century later.
Through all these actions, they gave the Jewish people new hope, showing them that the nation could continue even under the new circumstances, with its Torah and traditions (Oral Law) clarified and accessible.
Rabbi Yohanan ben Zakkai, disciple of Hillel, found favor in the eyes of the Roman leader Vespasian, for a reason explained in the Talmud (Gittin 56a-b), and was granted a request. He asked that the Romans (who had already begun the siege of Jerusalem) spare the town of Yavneh and its Torah-scholars. Vespasian acquiesced (Talmud, ibid), and Rabbi Yohanan gathered whatever Torah-sages he could, to Yavneh.After the Destruction during which the Romans razed Jerusalem, it was these sages (Rabbi Eliezer, Rabbi Yehoshua, Rabbi Akiva and many others) who redeemed Jewish captives, distributed charity, and rebuilt whatever they could. (Compare this to the Sadducees, who melted into the background and did not lift a finger to help the people.)
Since he spent his last years in the town of Bror Chayil, he likely died there. His death was around the year 76 CE.
Yohanan Friedmann was born in 1936.
Yohanan Aharoni died in 1976.
Yohanan Aharoni was born in 1919.
Ramat Yohanan was created in 1932.
Yohanan Danino was born in 1959.
Yohanan Levi was born in 1901.
Yohanan Levi died in 1945.
Yohanan Cohen was born in 1917.
Ganei Yohanan was created in 1950.
he was remembered for convincing the roman General Vespasian to set aside a place for Jewish scholars to study during the time that Rome had taken over Israel.