How did the Jerusalem Talmud and Babylonian Talmud begin in different Jewish academies?

The Jerusalem and Babylonian Talmuds originated from the work of the amoraim (interpreters), who provided commentary on the Mishna. The foundations for these works were established by three disciples of Judah ha-Nasi in distinct geographical centers of learning:12

• Jerusalem (Palestinian) Talmud: Its foundations were laid by Joḥanan bar Nappaḥa in academies located in Tiberias and other Palestinian centers such as Sepphoris, Caesarea, and Lydda.12
• Babylonian Talmud: Its foundations were laid by Rav (Abba Arika) and Samuel bar Abba in the academies of Sura and Nehardea in Babylonia. Later, additional prominent academies were established in locations such as Pumbedita, Mahoza, and Naresh.12

While the academies maintained communication—with students frequently traveling between Palestine and Babylonia—they developed different methods of study. For instance, Pumbedita emphasized casuistry, while Sura focused on breadth of knowledge. These regional differences, combined with distinct linguistic dialects and the influence of local laws (such as Persian law in Babylonia), resulted in two unique, autonomous compilations.12