When I bought the 19 coin lot, seeing this one in the description was honestly what made me pull the trigger. This is a very scarce and highly important historical coin.
Nezak-Alchon alliance (c. 580-680)
AE Drachm, 22mm, 3.03g
Nezak Trident-type bust right, Sankh shell before
Alchon tamgha in ornate design
While the Kidarites were the first Huns to invade India in c.400 AD, it was the Alchon huns who pushed the deepest into India to the most consequence. From the Indian sources, the Alchons were a good analogy to the Vikings; they raided the treasures of the monastery, killed monks and priests, and sometimes levelled whole towns. The tide turned in 528 when the Alchon ruler Mihirakula was defeated by an alliance of Indian kingdoms, led by Yasodharman. Hunnic strongholds were eliminated by 545.

History goes dark at that point, leaving only the coins to tell the story. It appears that the Alchons were driven into Kabulistan, where they made peace with their former enemies, the Nezak huns.

Alchon tamgha:

There were two basic types of these crossover drachms; this type where the Alchon tamgha takes the place of the fire altar reverse, and another standard Napki Malka type with the tamgha added somewhere in the obverse field. The Huns were finally subjugated by the Western Turks in about 680, although the Turks largely based their coinage on Nezak designs.
A couple centuries later, the Western Turks were replaced by the Hindu Shahis, giving us the much more common Bull & Horseman jitals.