Posidonius of Olbia (Ποσειδώνιος ὁ Ὀλβιοπολίτης) was a minor Greek historian of the 1st century BCE, a native of the Pontic colony of Olbia. He is distinguished from the Stoic philosopher Posidonius of Apamea [1, 2]. Beyond this, no biographical details are recorded.

His sole known work is a lost local history, On the Customs of the Sauromatians (Περὶ τῶν Σαυροματῶν ἤθῶν), which survives only in fragments. These are preserved primarily through quotations in Strabo’s Geographica [1, 2].

Posidonius is significant as a source of ethnographic information on the peoples north of the Black Sea, particularly the Sarmatians (Sauromatians). His work, utilized by Strabo, contributes to the Greco-Roman understanding of the Pontic steppe from the perspective of a Greek colony on the periphery of the Hellenistic world [1, 2].

Sources 1. Oxford Research Encyclopedia of Classics: Posidonius of Olbia: https://oxfordre.com/classics/view/10.1093/acrefore/9780199381135.001.0001/acrefore-9780199381135-e-5206 2. ToposText: Posidonius of Olbia: https://topostext.org/people/1440