Leo Lucassen tackles the question of whether the integration process of these recent immigrants will fundamentally differ in the long run (over multiple generations) from the experiences of similar immigrant groups in the past. For comparison, Lucassen focuses on "large and problematic groups" from Western Europe's past (the Irish in the United Kingdom, the Poles in Germany, and the Italians in France) and demonstrates a number of structural similarities in the way migrants and their descendants integrated into these nation states. Lucassen emphasizes that the geographic sources of the "threat" have changed and that contemporaries tend to overemphasize the threat of each successive wave of immigrants, in part because the successfully incorporated immigrants of the past have become invisible in national histories.