The Yeda 嚈噠, also called Henda 噷噠, Xianda 囐噠, Yida 挹怛, Yida 挹達, Yitian 挹闐, Huo 活 or Hua 滑, were by the Greeks called "Hephthalites" and by the Indians "White Huns". They were probably an Indo-Iranian people living in the region of modern Uzbekistan (the Soghdiana), where they had migrated to from a place more northwards during the 370s CE.
During the 420s they crossed the River Amu Darya and invaded the Sasanian empire of the Persians but they were repelled. Around ten years later they were able to conquer the region of Tokharistan (whose inhabitants were by the Chinese called Yuezhi 月氏), just north of the Hindukush Range. From this place they regularly raided Persia and the kingdom of Kushana (by the Chinese called Guishuang 貴霜) in what is today Afghanistan. From then on they regularly defeated the Persian armies, first in 453, and then in 484, when they occupied the province of Khorazan.
For several decades the Persians had to deliver tributes to the Yeda. At the beginning of the 6th century the steppe federation of the Gaoche 高車 was a challenge for the Yeda empire. Both peoples fought in the Dzungar Basin, and the Yeda remained superior. They used this victory to take control over the city states of the Tarim Basin (see Silk Road). They destroyed the rest of the Kushan states and invaded India and advances as far as the state of Magada. Only the united force of several Indian kingdoms could throw them back to the River Indus. Around 560 the Sassanid dynasty in Persia allied with the newly emerging steppe federation of the Türks (by the Chinese called Tujue 突厥). This alliance finally destroyed the expansive empire of the Yeda, and their people disappeared.
The Yeda were pastoral nomads, and only a small number of them settled down. They had their own ways of jurisdiction. The death were buried in a wooden coffin, above which stones were piled up. Polyandric marriages, like the Tibetans do, were commonly seen among the Yeda. With the contact to Persia, the religions of Zoroastrianism and Nestorianism became widespread. The Yeda had no script, so that no documents are preserved written in their language. Therefore it is not easy to determine their ethnic affiliation.