"If I have found any specific group of people to be the subject of the most insidious contemporary forms of racial discrimination, those are migrants," he said. "And I think in many parts of the world today, immigrants bear the brunt of xenophobic intolerance — and this is true of the United States, and it is of Europe, and it is of many parts of the world."Obviously xenophobia, which literally means fear of strangers, is going to be aimed especially at immigrants. The fact that the word comes from the ancient Greeks tells us that this is something that human societies have been dealing with forever. Having said that, however, it is nonetheless important to be regularly reminded that if immigrants are appropriately integrated into the host society, they then become the in-group members.
On a related note, the MSNBC site from which this story was pulled also has a very useful time-line of immigration to the United States.