Sforno on Genesis 10:10/ספורנו על בראשית י׳:י׳

1ותהי ראשית ממלכתו בבל, the Torah mentions this to explain that because of Nimrod’s powerful and relatively civilised kingdom all the people moved to the valley of Shinor to be within the orbit of his power and influence. The illusion of great power, augmented by unity of purpose, led to their insurrection against G’d, and to their downfall. Central symbols always exercised a gravitational pull on people’s minds, as we see even among the Jewish people in the efforts by Jerobam to counteract the centrality of the Temple in Jerusalem. (Kings I 12,26)