He is sometimes identified with the Thoas who was the king of Lemnos and the son of Dionysus and Ariadne, and the father of Hypsipyle.
[3] According to the Greek grammarian Antoninus Liberalis, the 2nd-century BC poet Nicander said that Thoas was the son of Borysthenes,[4] god of a major river to the far north of Greece (now the Dnieper).
In Euripides' play, Iphigenia among the Taurians, Iphigenia, after being rescued from her intended sacrifice at Aulis by Artemis, has been brought to the Taurians and their king Thoas, where she is forced to sacrifice any trespassing Greeks to Artemis.
Iphigenia meets with Thoas and claims that because of Orestes' sin of matricide he is polluted and needs to be purified by being washed in the sea.
Hyginus provides an ending to Thoas' story, saying that the king pursued Orestes and Iphigenia, to the island home of Chryses, the son of Agamemnon and his Trojan war-prize Chryseis.