Complex sentence: Some historians have dated the Székely presence in the Eastern Carpathians as early as the 5th century, and found historical evidence that the Székelys were part of the Avar confederation during the so-called Dark Ages, but this does not mean that they were ethnically Avar.
Split into simpler sentences: Some historians have dated the Székely presence in the Eastern Carpathians as early as the 5th century. There is historical evidence that the Székelys were part of the Avar confederation during the so-called Dark Ages, but this does not mean that they were ethnically Avar.