Parthian shot
The Parthian shot is a light cavalry hit-and-run tactic used by horse archers. By making a real or feigned retreat at full gallop, the riders turn their bodies around to shoot the often slower, heavier armored pursuing enemies. First used by the Parthians, an ancient Iranian empire, it continued to be used by multiple civilizations especially those of Eurasian nomadic origins throughout the medieval period.
"Parthian shot" is also used metaphorically to describe a barbed insult delivered as the speaker departs.