For centuries, states have expelled parts of their populations to other regions within their borders or abroad, seeking to remove from areas threatened by a foreign or internal enemy those whose loyalty they questioned, to facilitate unpopular policies, or to seize lands for more favored groups. Mass deportations differ in principle from the exile of convicts. Convicts are sentenced for certain crimes to specific terms of exile after routine court procedures, whereas deportations are often preemptive, targeting not individuals but groups of potential troublemakers defined on the basis of ethnicity, race, religion, or class, and victims usually are exiled forever by emergency decrees. Depending on the objectives and nature of the state, deportation could be more or less painful to its victims. In the nineteenth century, it was a routine colonial practice, and during World War I, many states exiled or interned citizens who shared ethnicity with enemy nations. Germany deported many Poles and Jews and planned to remove all Slavs from eastern frontier regions, Austria-Hungary expelled Serbs from occupied lands, and Canada interned recent immigrants from Austria-Hungary. In 1915, the Ottomans deported the Armenians who escaped slaughter from the Russian border to Syria. In the 1920s, Greece, Bulgaria, and Turkey exchanged diaspora populations to forestall security problems, and in the 1930s, the Nazis expelled Jews from Germany.