Between 653 and 333 BC, both Colchis and Iberia survived successive invasions by the Iranian Median Empire. The case is different for the Achaemenid Persians however. According to Herodotus (3.97), Achaemenid power extended as far as the Caucasus mountains, but the Colchians are not included in his list of the twenty Persian satrapies. Nor are they referred to in the lists of Achaemenid lands (dahyāva) given in the Old Persian inscriptions of Darius and his successors. In Xenophon's Anabasis (7.8.25; probably an interpolation) the tribes of Colchis and East Pontus are referred to as independent (autónomoi). On the other hand, Herodotus mentioned both the Colchians and various Pontic tribes in his catalogue (7.78-79) of approximately fifty-seven peoples who participated in Xerxes’ expedition against Greece in 481-80 BCE. As the "Encyclopaedia Iranica" states, it is thus probable that the Achaemenids never succeeded in asserting effective rule over Colchis, though local tribal leaders seem to have acknowledged some kind of Persian suzerainty. The "Encyclopaedia Iranica" further states, whereas the adjoining Pontic tribes of the nineteenth satrapy and the Armenians of the thirteenth are mentioned as having paid tribute to Persia, the Colchians and their Caucasian neighbors are not; they had, however, undertaken to send gifts (100 boys and 100 girls) every five years (Herodotus 3.97).