Theonesios I was a King of Characene,E. Yarshater, The Cambridge History of Iran, Cambridge University Press page 487 a vassal state of the Parthian empire and important trading port on the Persian Gulf. His rule was from 25/24BC to 19/18BC. Richard Nelson Frye, The History of Ancient Iran(C.H.Beck, 1984) p277.
He is known only from his silver Tetradrachms, which exhibits various spelling of his name.Monika Schuol, The Characene: A Mesopotamian Kingdom in Hellenistic times. Steiner, Stuttgart 2000, page 225, 316-317.
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