What is "derbices"

Derbices or Derbikes were a small pocket of tribal people located at or around Hyrcania, which is an area located in the northern borders of the Iranian Plateau. Most of what history can recount of this tribe is from the writings of Ctesias. Led by their leader, Amoraeus, Derbices led a rebellion against Cyrus the Great causing the mortal wounding of the king. They are however eventually defeated by Cyrus and incorporated into the Persian Empire. It is critical to note that the account of Derbices is basically the work of Ctesias and offers one of the plausible versions by which Cyrus the Great is killed. Other plausible accounts include that of Herodotus which revolves around the Massagatae, and various other versions including one by Xenophon which states Cyrus the Great actually died peacefully at his palace. Regardless, this article (and Derbices by association) makes sense in the context of historical reportings of Ctesias, which according to at least a few historians is the most credible version (along with that of Herodotus) since "...he [Cteias] had been a long while in Persia as a doctor."