The Hephthalites (ηβοδαλο), sometimes called the White Huns (also known as the White Hunas, in Iranian as the Spet Xyon and in Sanskrit as the Sveta-huna), were a people who lived in Central Asia during the 5th to 8th centuries CE. They formed an empire, the Imperial Hephthalites, and were militarily important from 450 CE, when they defeated the Kidarites, to 560 CE, when combined forces from the First Turkic Khaganate and the Sasanian Empire defeated them. After 560 CE, they established "principalities" in the area of Tokharistan, under the suzerainty of the Western Turks (in the areas north of the Oxus) and of the Sasanian Empire (in the areas south of the Oxus), before the Tokhara Yabghus took over in 625.
The Imperial Hephthalites, based in Bactria, expanded eastwards to the Tarim Basin, westwards to Sogdia and southwards through Afghanistan, but they never went beyond the Hindu-Kush, which was occupied by the Alchon Huns, previously mistakenly regarded as an extension of the Hephthalites. They were a tribal confederation and included both nomadic and settled urban communities. They formed part of the four major states known collectively as Xyon (Xionites) or Huna, being preceded by the Kidarites and by the Alkhon, and succeeded by the Nezak Huns and by the First Turkic Khaganate. All of these Hunnic peoples have often been linked to the Huns who invaded Eastern Europe during the same period, and/or have been referred to as "Huns", but scholars have reached no consensus about any such connection.
The stronghold of the Hephthalites was Tokharistan (present-day southern Uzbekistan and northern Afghanistan) on the northern slopes of the Hindu Kush, and their capital was probably at Kunduz, having come from the east, possibly from the area of Badakhshan. By 479 the Hephthalites had conquered Sogdia and driven the Kidarites eastwards, and by 493 they had captured parts of present-day Dzungaria and the Tarim Basin (in present-day Northwest China). The Alchon Huns, formerly confused with the Hephthalites, expanded into Northern India as well.