Transylvania was part of the Austro-Hungarian empire until after World War I, when the ethnic Romanian majority in Transylvania created Romania.
Since the revolution to overthrow communism in 1989, both Hungarian and Romanian nationalism has increased, escalating latent tensions between these two groups. The disputed status of Transylvania remains central to this dynamic. The Hungarian minority in Transylvania has argued for regional autonomy by aligning their goals with the European Union and its support of regional integration. Given the legacy of border changes in this region, the Romanian State perceives these claims for Hungarian autonomy in Transylvania as a potential threat to their sovereignty and territory.
https://www.causes.com/actions/1725889-autonomie-pentru-transilvania