Callimedon expedition

The Callimedon expedition was a Siberian expedition led by Callimedon of Side in 246. The expedition was commissioned by the Seleucid king Seleucus XIII Heraclytenus to explore deeper into Eastern Siberia. Its purpose was to explore lands beyond Hyperbosia and make contact with the fabled Boreades, giants that held soveriengty over Hyperborea. It disappeared after its last recorded existence from 249, and remains one of the world's greatest mysteries, and it conjured a rumor that they were taken in by the Boreades and killed.

From its disappearance, another expedition was to be undertaken by Myron of Athenadoria, but the king decided to forfeit it under fear of Hyperborean invasion. Consequently, other explorative expeditions to Siberia, with the exception of envoy missions to Hyperbosia, were permanently suspended.