A historian using the historical thinking skill of chronological thinking might put evens that took place in history in "chronological order" in the hopes of understanding why certain events took place after others. This helps the historian determine "cause and effect".
They came mostly from Latin America and Asia. I know this because during that time the war in south Korea was going on and a lot of immigrants from that area came flooding in trying to get away from the war. Hope I helped. :)