Wikipedia
The Székelys , sometimes also referred to as Szeklers (, , , ), are a subgroup of the Hungarian people living mostly in the Székely Land in Romania. A significant population descending from the Székelys of Bukovina lives in Tolna and Baranya counties in Hungary and in certain districts of Vojvodina, Serbia. In 1952 the former province of Mureş (with the highest concentration of Székely population) was legally designated as the Hungarian Autonomous Region. It was superseded in 1960 by the Mureş-Hungarian Autonomous Region, itself divided in 1968 into three non-autonomous districts, Harghita, Covasna and Mureş.
In the Middle Ages, the Székelys, along with the Transylvanian Saxons, played a key role in the defense of the Kingdom of Hungary against the Ottomans in their posture as guards of the eastern border. With the Treaty of Trianon of 1920, Transylvania (including the Székely Land) became part of Romania, and the Székely population was a target of Romanianization efforts. In post- Cold War Romania, where the Székelys form roughly a half of the ethnic Hungarian population, members of the group have been among the most vocal of Hungarians seeking an autonomous Hungarian region in Transylvania. They were estimated to number about 860,000 in the 1970s and are officially recognized as a distinct minority group by the Romanian government. However, the Romanian government does not recognize the existence of a Székely Land.
Today's Székely Land roughly corresponds to the Romanian counties of Harghita, Covasna and central and eastern Mureş. Based on the official 2011 Romanian census, 1,227,623 ethnic Hungarians live in Romania, mostly in the region of Transylvania making 19.6% of the population of this region. Of these, 609,033 (according to the 2011 Romanian Census) live in the counties of Harghita, Covasna and Mureş, which taken together have a Hungarian majority (58%). The Hungarians in Székely Land therefore account for half (49.41%) of the Hungarians in Romania. When given the choice on the 2011 Romanian census between ethnically identifying as Székely or as Hungarian, the overwhelming majority of the Székelys chose the latter - only 532 persons declared themselves as ethnic Székely.