HALYS was a River-God of Paphlagonia and Pontos in Anatolia (modern Turkey).
The River Halys had its source on the Armenian plateau, issuing into the Black Sea near the Greek colony of Sinope on the border of Paphlagonia and Pontos. The major neighbouring rivers were the Parthenios to the west, and Thermodon to the east.
Apollonius Rhodius, Argonautica 2. 944 ff (trans. Rieu) (Greek epic C3rd B.C.) :
"The Assyrian coast [of the Black Sea], where Zeus himself had once given a home to Sinope daughter of Asopos, granting her the boon of virginity. He was trapped by his own promise. In his passion for the girl he had solemnly sworn to fulfil her dearest wish, whatever that might be; and she very cleverly had said, `I wish to remain a virgin.' By the same ruse the outwitted Apollon when he made love to her; and the River-God Halys as well."
Valerius Flaccus, Argonautica 5. 109 ff (trans. Mozley) (Roman epic C1st A.D.) :
"Embosoming Assyrian bays stands rich Sinope, once a Nympha and onw who mocked Jove’s [Zeus’] ardent wooing, unmoved by heavenly suitors; not Halys [the local River-God] only or Apollo were deceived by the trickery of the Nympha they loved."
- Apollonius Rhodius, The Argonautica - Greek Epic C3rd B.C.
- Valerius Flaccus, The Argonautica - Latin Epic C1st A.D.