Complex sentence: They assembled at Kápolna and started negotiations with the counts of the Székelys and the delegates of the Saxon seats, although the representatives of the noblemen, Székelys and Saxons had never held a joint assembly without the authorization of the monarch.
Split into simpler sentences: They assembled at Kápolna and started negotiations with the counts of the Székelys and the delegates of the Saxon seats. The representatives of the noblemen, Székelys and Saxons had never held a joint assembly without the authorization of the monarch.