They wanted to avoid racism and segregation and get jobs in industrialized civilized cities in the North. World War 2 helped because it opened a lot of job positions that needed to be filled because of the mass production of war necessities. Migration helped them establish themselves because the South was always cruel to them. <span />
No, it is technically false that <span>Buddhism spread only by means of overland routes, sine sea routes were involved as well--however land routes were far more prominent. </span>