Complex sentence: Bulgarians also applied the word to Turnovgrad, one of the capitals of the Bulgarian tsars, but after the Balkans fell under Ottoman rule, the Bulgarian word has been used exclusively as another name of Constantinople.
Split into simpler sentences: Bulgarians also applied the word to Turnovgrad, one of the capitals of the Bulgarian tsars. Since the Balkans fell under Ottoman rule, the Bulgarian word has been used exclusively as another name of Constantinople.