Çoruh River
According to Theodoret of Cyrrus (5th century AD), the Sanni and Lazi were two different tribes. In the first centuries AD, Sanni people living in the region of Trebizond were paying tribute to the Roman Empire. However, they tried to avoid heavy direct taxation and later left the coastal areas for the mountains. In the 6th century, Procopius still mentions them as living near the source of the Boasi (today the Chorokhi, or Çoruh River).