Development of the number of Hungarians in Czechoslovakia between the two World Wars. Colonisation of Slovaks and Czechs on Slovak territories lived by Hungarians within the framework of the land reform in 1919. Slovak and Czech colonies set up within the framework of official and private colonisation. Percentage of Hungarian and Slovak population in colonised villages that lost their absolute Hungarian majority and in colonised villages that became of mixed character.

While the Hungarian population census in 1910 recorded on Slovakia’s territory 896 271, the Czechoslovak population census in Slovakia in 1930 recorded only 592 337 Hungarians. Thus, the decrease in the number of population exceeded 300 000, that is one-third of the number recorded in 1910, the number of lost villages was 123.

This immense change in the number of ethnical rate – of which reasons can be traced back beside the moving of 100 000 Hungarians to the territories of Hungary also to introducing the Jewish national category and to the changing of nationalities of the bilingual population – was present mainly on Slovak ethnical territories and towns lying on the language boundary, and after the Turkish wars in the 18th C partially the territories with mixed ethnicity resettled with Slovaks. Thus, the Czechoslovak authorities accredited to the Land reform in 1919 a major role in slovakisation and colonization of closed territories with Hungarian ethnicity, during which Slav (Slovak and Czech) settlers, so-called colonists settled on the territories of Southern Slovakia lived by Hungarians. The number of these settlers exceeded 2000, 8-10 thousand with family members, and the number of colonies created for them was over hundred.

The colonies were situated by the organizations who directed colonization at such places that were strategically considered to be the most important points of Slovak-Hungarian language boundaries in such a way that it divided the Hungarian ethnical line and they moved the language boundary to south. Some towns with Hungarian population, e.g. Szene, Galanta, Komárom, Losonc (Lucenec), and Rimaszombat (Rimavská Sobota), were surrounded with a real circle of settlement villages.

Practically, the colonies covered all the Hungarian language territory, although in consequence of the crisis of world economy the settlements got out of breath to the beginning of the 1930s, since their extent lacked behind the original conceptions. In spite of this, in many places the ethnical rate was changed in such extent that the population census in 1930 in villages that were completely lived by Hungarians – in which not only by the Hungarian population census in 1930, but also in the Czechoslovak population census in 1921 found just a few Slovaks – recorded numerous Slovaks (and Czechs), and even some of the villages lost their Hungarian majority.