Tiridates I of Parthia is a figure shrouded in historical ambiguity, often regarded as the brother of Arsaces I, the founder of the Parthian kingdom. According to Arrian in his work, Parthica, Tiridates is said to have succeeded Arsaces around two hundred forty-six BC. However, modern historians cast doubt on the veracity of Arrian's account, suggesting that Tiridates may be a fictional character and that Arsaces continued to rule until two hundred seventeen BC.
During a tumultuous period marked by the disintegration of the Seleucid Empire, Tiridates briefly held power in Parthia amidst the chaos instigated by Ptolemy III's incursions around two hundred forty-six BC. His reign was short-lived, as he faced defeat and was expelled by Seleucus II around two hundred thirty-eight BC. Yet, the tides turned when Seleucus was compelled to return west due to a rebellion led by his brother, Antiochus Hierax.
Seizing the opportunity, Tiridates returned to Parthia and managed to defeat the Macedonian forces. In a significant move, he adopted the name of his brother, Arsaces, a tradition that would be followed by subsequent Parthian kings. This act not only solidified his claim to the throne but also linked his legacy to that of the founding dynasty.