Complex sentence: The ethnic Hungarian population of Transylvania, largely composed of Székelys, form a majority in the counties of Covasna (73.6%) and Harghita (84.8%).
Split into simpler sentences: The ethnic Hungarian population of Transylvania, largely composed of Székelys, form a majority in the counties of Covasna and Harghita. The population is mostly of Hungarian ethnicity in Harghita County (84.8%) and Covasna County (73.6%).