If a state puts extreme emphasis on a homogeneous national identity, it may resort, especially in the case of minorities originating from historical foes, to harsh, even extreme measures to 'exterminate' the minority culture, sometimes to the point of considering the only alternative its physical elimination. States, mostly based on the idea of nation, perceived the presence of ethnic or linguistic minorities as a danger for their own territorial integrity. In fact minorities could claim their own independence, or to be rejoined with their own motherland. The consequence was the weakening or disappearing of several ethnic minorities. Forced migrations took place after each of the two world wars. The latter half of the 19th century and the first half of the 20th century saw the rise of nationalism. Previously, a country consisted largely of whatever peoples lived on the land that was under the dominion of a particular ruler. Thus, as principalities and kingdoms grew through conquest and marriage, a ruler could wind up with peoples of many different ethnicities under his dominion. This also reflected the long history of migrations of different tribes and peoples through Europe. The concept of nationalism was based on the idea of a "people" who shared a common bond through race, religion, language and culture. Furthermore, nationalism asserted that each "people" had a right to its own nation. Much of European history in the latter half of the 19th century and the first half of the 20th century can be understood as efforts to realign national boundaries with this concept of "one people, one nation". Such scenes also happened in Japan and Korea, as the two countries stated themselves as a single-nation country, ethnic minorities had to hide their national identity for centuries, and many resulted in assimilation, such as Ainu and Ryukyuan people in Japan, migrants of Goguryeo, Balhae and Tungusic peoples in Korea. Much conflict would arise when one nation asserted territorial rights to land outside its borders on the basis of a common bond with the people living on that land. Another source of conflict arose when a group of people who constituted a minority in one nation would seek to secede from the nation either to form an independent nation or join another nation with whom they felt stronger ties. Yet another source of conflict was the desire of some nations to expel people from territory within its borders on the ground that those people did not share a common bond with the majority of people living in that nation. It is useful to contrast the mass migrations and forced expulsion of ethnic Germans out of Eastern Europe with other massive transfers of populations, such as population exchange between Greece and Turkey, and population exchanges that occurred after the Partition of India. In all cases those expelled suffered greatly. In the United States and Canada, forced assimilation had been practiced against indigenous peoples through the Indian residential school system and Indian boarding schools. At least one million members of China's MuslimUyghur minority have been detained in mass detention camps in Xinjiang, termed "reeducation camps", aimed at changing the political thinking of detainees, their identities, and their religious beliefs. In December 2017, Reuters reported that "Ukraine’s neighbors have a right to criticize a new Ukrainian law banning schools from teaching in minority languages beyond primary school level, a leading European rights watchdog said". Beginning in 2019, instruction in Russian language will be gradually discontinued in private colleges and universities in Latvia, as well as general instruction in Latvian public high schools. Permanent Representative of the Russian Federation to the Organization for Security and Co-operation in Europe Alexander Lukashevich has denounced the reform as a "discriminatory policy with the goal of forced assimilation of the Russian-speaking population."
When new immigrants enter a country, there is a tension as they adapt to new people and surroundings to fit in, while holding on to their original culture. Here, studies show that native inhabitants often expect assimilation especially from negatively viewed immigrants. Moreover, assimilation pressure seems to be particularly pronounced toward the second generation of these immigrants.
