The Huna (also known as Indo-Hephthalites or Alchon), as they were known in South Asia, seem to have been part of the Hephthalite group, who established themselves in Afghanistan by the first half of the fifth century, with their capital at Bamiyan. They sometimes call themselves "Hono" on their coins, but it is unknown how related they may have been to the Huns who invaded the Western world.
The Bhishma Parva of the Mahabharata, supposed to have been edited around the 4th or 5th century, in one of its verses, mentions the Hunas with the Parasikas and other Mlechha tribes of the northwest including the Yavanas, Chinas, Kambojas, Darunas, Sukritvahas, Kulatthas etc . According to Dr V. A. Smith, the verse is reminiscent of the period when the Hunas first came into contact with the Sassanian dynasty of Persia .
Scholars believe that king Raghu, the hero of Kalidasa's Sanskrit play Raghuvamsha (4th/5th c AD) was in fact king Chandragupta Vikramaditya of the Gupta Dynasty. He had started a military expedition and after defeating and subjugating the local peoples along the way he reached the Parasikas of Sassanian Iran and defeated them after fierce fighting. Then he proceeded to north from Iran and reached river Vamkshu (or Oxus) where he battled with the Hunas. After conquering the Hunas, he crossed the Oxus and encountered the Kambojas, an ancient Iranian people who find frequent mention in South Asian texts .
Brahat Katha of Kashmiri Pandit Kshmendra (11th c AD) also claims that king Vikramaditya had slaughtered the Shakas, Barbaras, Hunas, Kambojas, Yavanas, Parasikas and the Tusharas etc and hence unburdened the earth of these sinful Mlechhas . There is still another ancient Brahmanical text Katha-Saritsagara by Somadeva which also attests that king Vikramaditya had invaded the north-west tribes including the Kashmiras and had destroyed the Sanghas of the Mlechhas (reference to Sanghas here obviously alludes to the Sanghas of the Madrakas, Yaudheyas, Kambojas, Mallas or Malavas, Sibis, Arjunayans, Kulutas and Kunindas etc). Those who survived accepted his suzerainty and many of them joined his armed forces .
These references suggest that the Guptas indeed had encounters with the Hunas from the north-west.
Skandagupta is stated to have repelled a Huna invasion in 455, but they continued to pressure South Asia's northwest frontier (present day Pakistan), and broke through into northern India by the end of the fifth century, hastening the disintegration of the Gupta Empire.
According to Litvinsky, the initial Huna or Alxon raids on Gandhara took place in the late 5th and early 6th centuries AD, upon the death of the Gupta ruler, Skandagupta (455-470), presumably led by the Tegin Khingila. M. Chakravary, based on Chinese and Persian histories believes that the Hunas conquered Gandhara from the Ki-to-lo (Kidarites) in ca. 475 AD. Gandhara had been occupied by various Kidarite principalities from the early 4th century AD, but it is still a subject of debate as to whether rule was transferred from the Kidarites directly to the Hephthalites. It is known that the Huns invaded Gandhara and the Punjab from the Kabul valley after vanquishing the Kidarite principalities.
The Alchon ruler Toramana established his rule over Gandhara and western Punjab, and was succeeded by his son Mihirakula in 520 whose capital was Sakala or modern day Sialkot in the Pakistani Punjab. The Guptas continued to resist the Hunas, and allied with the rulers of the neighboring Indian states.
The Hunas suffered a defeat by Yasodharman of Malwa in 528, and by 542 Mihirakula had been driven off the plains of northern India, taking refuge in Kashmir, and he is thought to have died soon after. Mihirakula is remembered in contemporary Indian and Chinese histories for his cruelty and his destruction of temples and monasteries, with particular hostility towards Buddhism.
After the end of the sixth century little is recorded in India about the Huna, and what happened to them is unclear; some historians surmise that the remaining Huna were assimilated into northern South Asia's population.
The Gurjara clan appeared in northern India about the time of the Huna invasions of northern India, and later established a number of ruling dynasties in northern India, including the Pratiharas of Kanauj. Gurjara origins and their relationship to the Hephthalites are not well documented, and subject to considerable debate. However, Huna is one of the prominent gotras among Gurjars and many Huna (Gurjar) villages can still be found in Ghaziabad and Bulandshahr.
The Hunas are mentioned in the Tibetan chronicle Dpag-bsam-ljon-bzah (The Excellent Kalpa-Vrksa''), along people like the Yavanas, Kambojas, Tukharas, Khaqsas, Daradas etc . .