Ethnic Hungarians are demanding autonomy in Romanian communities. Transylvania was part of the Austro-Hungarian Empire until after World War I, when the ethnic Romanian majority created their own country.
About 10,000 people held protests on Sunday in Hungary and Romania to demand autonomy for the 1.2 million ethnic Hungarians living in Romania.
The marches - with people singing, waving Hungarian flags, and riding horses and carriages - happened in communities of Transylvania, including the town of Targu Secuiesc.
The Democratic Union of Hungarians in Romania organized the marches. In Hungary, thousands took part in demonstrations in Budapest and other cities to show solidarity.
Hungarians compose about 6 percent of Romania's population. Their leader, Kelemen Hunor, told The Associated Press news agency on Sunday that they want territorial autonomy to maintain their ethnic identity and grow economically.
Romanian politicians have opposed granting the minority that status.