The earliest mentions of Slavic raids across the lower River Danube may be dated to the first half of the 6th century, yet no archaeological evidence of a Slavic settlement in the Balkans could be securely dated before c. 600 AD.
No archaeological evidence of a Slavic settlement in the Balkans could be securely dated before when?
{'text': 'c. 600 AD', 'answer_start': 219}