The oppression of minorities has been a major theme in the history of Europe. It has been a leading cause of disputes over territory, often resulting in war. In modern times nation states have demanded the undivided loyalty of their citizens. This has led to discrimination and racism, and often to the persecution, at its most extreme in the Nazi crusade against the Jews. Recent years have seen Ceausescu's persecution of Hungarians and ethnic cleansing in the Balkans. Minorities, represented by organisations such as the Basque ETA and the Northern Irish Catholic IRA, are also responsible for many of acts of terrorism.

Outsiders is the first history of all European minority communities by a single author. Panikos Panayi deals with the classic dispersed minorities, the Jews and the Gypsies, as well as the Muslims of the Balkans and the massive diaspora of Germans in eastern Europe from the middle ages to 1945. Almost all countries have disadvantaged ethnic and linguistic minorities: whether minorities without their own states, such as the Bretons, Scots, Vlachs and Kurds; or those, such as the Russians in Estonia or the Greeks in Turkey, who form linguistic and ethnic groups different to the native majorities. During wars, and in particular the Second World War, the existence of alien communities often led to persecution, in turn bringing about huge refugee migrations. The result has been untold suffering and the massive resettlement of European populations.

Since the Second World War, the demand for cheap labour has led to an influx of immigrants from outside Europe, whether from the Caribbean, India or Africa. This followed an earlier wave, in which workers from the relatively poor Mediterranean countries travelled north to the industrial heartlands. There has also been a massive migration westwards of German-speakers. Although all EEC countries now operate strict controls on immigrants, there is enormous pressure from both the east, following the fall of Communism, and from the third world, where birth-rates greatly outstrip that of Europe. The existence of this pressure, as well as that of already sizeable non-European minority communities in all European countries, is an inevitable determinant of Europe's history in the twenty-first century.