Nezak Huns in the context of "Alchon Huns"

The Hephthalites (Bactrian: ηβοδαλο, romanized: Ebodalo), sometimes called the White Huns (also known as the White Hunas, in Iranian as the Spet Xyon and in Sanskrit and Prakrit as the Sveta-huna), were a people who lived in Central Asia during the 5th to 8th centuries CE, part of the larger group of Eastern Iranian Huns. 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 thought to be 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 controversially 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 Turk Shahis were a dynasty of Western Turk, or mixed Turco-Hephthalite origin, that ruled from Kabul and Kapisa to Gandhara in the 7th to 9th centuries AD. They may have been of Khalaj ethnicity. The Gandhara territory may have been bordering the Kashmir kingdom to the east. From the 560s, the Western Turks had gradually expanded southeasterward from Transoxonia, and occupied Bactria and the Hindu Kush region, forming largely independent polities. The Turk Shahis may have been a political extension of the neighbouring Western Turk Yabghus of Tokharistan. In the Hindu Kush region, they replaced the Nezak Huns – the last dynasty of Bactrian rulers with origins among the Xwn (Xionite) and/or Huna peoples (who are sometimes also referred to as "Huns" who invaded Eastern Europe during a similar period).

The Turk Shahis arose at a time when the Sasanian Empire had already been conquered by the Rashidun Caliphate. The Turk Shahis then resisted for more than 250 years the eastward expansion of the Abbasid Caliphate, until they fell to the Persian Saffarids in the 9th century AD. The Ghaznavids then finally broke through into India after overpowering the declining subsequent Hindu Shahis and Gurjaras.

Hunas or Huna (Middle Brahmi script: Hūṇā) was the name given by the ancient Indians to a group of Central Asian tribes who, via the Khyber Pass, entered the Indian subcontinent at the end of the 5th or early 6th century. The Hunas occupied areas as far south as Eran and Kausambi, greatly weakening the Gupta Empire. The Hunas were ultimately defeated by a coalition of Indian princes that included an Indian king Yasodharman and the Gupta emperor, Narasimhagupta. They defeated a Huna army and their ruler Mihirakula in 528 CE and drove them out of India. The Guptas are thought to have played only a minor role in this campaign.

The Hunas are thought to have included the Xionite and/or Hephthalite, the Kidarites, the Alchon Huns (also known as the Alxon, Alakhana, Walxon etc.) and the Nezak Huns. Such names, along with that of the Harahunas (also known as the Halahunas or Harahuras) mentioned in Hindu texts, have sometimes been used for the Hunas in general; while these groups (and the Iranian Huns) appear to have been a component of the Hunas, such names were not necessarily synonymous. Some authors suggest that the Hunas were Hephthalite Huns from Central Asia. The relationship, of the Hunas to the Huns, a Central Asian people who invaded Europe during the same period, is under research.

The Alchon Huns, (Bactrian: αλχον(ν)ο Alkhon(n)o or αλχαν(ν)ο Alkhan(n)o) also known as the Alkhan, Alchono, Alxon, Alkhon, Alakhana, and Walxon, were a nomadic people who established states in Central Asia and the Indian subcontinent during the 4th and 6th centuries CE. They were first mentioned as being located in Paropamisus, and later expanded south-east, into the Punjab and Central India, going as far as Eran and Kausambi. The Alchon invasion of the Indian subcontinent eradicated the Kidarite Huns who had preceded them by about a century, and contributed to the fall of the Gupta Empire, in a sense bringing an end to Classical India.

The invasion of India by the Huna peoples follows invasions of the subcontinent in the preceding centuries by the Yavana (Indo-Greeks), the Saka (Indo-Scythians), the Pahlava (Indo-Parthians), and the Kushana (Yuezhi). The Alchon Empire was the second of four major Huna states established in Central Asia and the Indian subcontinent. The Alchon were preceded by the Kidarites and succeeded by the Hephthalites and Nezak Huns in Bactria and the Hindu Kush respectively. The names of the Alchon kings are known from their extensive coinage, Buddhist accounts, and a number of commemorative inscriptions throughout the Indian subcontinent.

The term Iranian Huns is sometimes used for a group of different tribes that lived in Central Asia, in the historical regions of Transoxiana, Bactria, Tokharistan, Kabul Valley, and Gandhara, overlapping with the modern-day Afghanistan, Tajikistan, Uzbekistan, Eastern Iran, Pakistan, and Northwest India, between the fourth and seventh centuries. They also threatened the Northeast borders of Sasanian Iran and forced the Shahs to lead many ill-documented campaigns against them.

The term was introduced by Robert Göbl in the 1960s and is based on his study of coins. The term "Iranian Huns" coined by Göbl has been sometimes accepted in research, especially in German academia, and reflects how some of the namings and inscriptions of the Kidarites and Hephthalites used an Iranian language, and the bulk of the population they ruled was Iranian. Their origin is controversially discussed. Göbl describes four groups: Kidarites, Alchons, Nezaks, and Hephthalites as the Iranian Huns based on numismatic evidence available at his time. But recent descriptions also put the Xionites as a fifth group. In recent research, it is debated whether the new arrivals came as one wave or several waves of different peoples.