Iastus
Ἰαστος
Iastus (Ἰαστος), a river which, according to Ptolemy (6.12), was, like the Polytimetus (Kohik), an affluent of the Caspian basin, and should in fact be considered as such in the sense given to a denomination which at that time embraced a vast and complicated hydraulic system. [JAXARTES] Von Humboldt (Asie Centrale, vol. ii. p. 263) has identified it with the Kizil-Deria, the dry bed of which may be traced on the barren wastes of Kizil Koum in W. Turkistan. It is no unusual circumstance in the sandy steppes of N. Asia for rivers to change their course, or even entirely to disappear. Thus the Kizil-Deria, which was known to geographers till the commencement of this century, no longer exists. (Comp. Levchine, Hordes et Steppes des Kirghiz Kazaks, p. 456.)
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.