Iastus
Iastus a river mentioned by Ptolemy (6.14.2) as falling into the Caspian between the Jaik and the Oxus. It is only safe to call it one of the numerous rivers of Independent Tartary.
From William Smith (ed.), Dictionary of Greek and Roman Geography. Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities and Tufts University. Data accessed from https://github.com/PerseusDL/canonical-pdlrefwk/ on 17 October 2026.