Complex sentence: The Kabarsa group of Khazars who rebelled against the Khaganjoined the Magyars in Etelköz, according to Porphyrogenitus, which shows that the Magyars had got rid of the Khagan's suzerainty.
Split into simpler sentences: The Kabarsa group of Khazars who rebelled against the Khaganjoined the Magyars in Etelköz, according to Porphyrogenitus. This report shows that the Magyars had got rid of the Khagan's suzerainty.