Biographical history, as taught in our public schools, is still largely a history of boneheads; ridiculous kings and queens, paranoid political leaders, compulsive voyagers, ignorant general the flotsam and jetsam of historical currents. The men who radically altered history, the great scientists and mathematicians, are seldom mentioned, if at all.
I think massive migration is inevitable. As sea levels rise, as climate change happens, as fertile fields become arid, as wars are fought, people are going to move. They always have.