Complex sentence: It refers to a members of rebel bands (chetas) operating in the Balkans during the final period of the Ottoman Empire and fighting against the Turkish authorities, which were supported by the governments of the neighbouring states, especially of Bulgaria.
Split into simpler sentences: It refers to a members of rebel bands (chetas) operating in the Balkans during the final period of the Ottoman Empire. They fought against the Turkish authorities and were supported by the governments of the neighbouring states, especially of Bulgaria.