ARAB, the anc. Araxes, Phasis (Xenophon), Ras (Turk ish and Arabian), Yerash (Armenian), Rashki (Georgian), a river which rises south of Erzerum, near the source of the Euphrates, in the Bingeul-dagh, and flows east through Arme nia. It is about 600m. long, and its chief tributary, the Zanga, flows by Erivan and drains Lake Gokcha. It is a rapid muddy stream, dangerous when swollen by the melting snows of Armenia, but fordable in its ordinary state. It formerly joined the Kura; but in 1897 it changed its course, and now runs directly into the Caspian. On an island in the river stood Artaxata, the capital of Armenia from 180 B.C. t0 A.D. 50.