Midrash Berashis Rabbah

Midrash Berashis Rabbah says that on the day that Rabi Akiva gave up his soul al Kiddush Hashem, Reb Yehudah HaNasi was born. A seven-generation descendent of Hillel HaZaken, Rebbe was the son of Rabban Shimon ben Gamlial, and of the royal line of Dovid HaMelech.