Xionites, Chionites, Chionitae, (Middle Persian: Xiyon, Avestan: Xiiaona, Sogdian:xwn), Hunni (Pahlavi:Huna, Yun (Chinese: Yǔn) or Xūn, are a nomadic tribe prominent in Transoxania and Bactria.

The Xionites arrived in the mid-4th century with the wave of immigration from Central Asia into Iran in late antiquity.

They had been influenced by the Kushan and Bactrian cultures, and became a threat on the northeastern frontier of the Sassanid Empire.