Bob beat me to the punch.
Nezak-Alchon alliance copper drachm, minted in present day Pakistan/Afghanistan around 600 AD.
The Alchon huns invaded India around the time the Gupta empire collapsed. Unlike most of the other invaders since the Vedic age, they had no interest in settling or integrating into the culture; they trashed ancient holy sites looking for valuables and raped and pillaged as they went. So the remnant of the Gupta empire along with other native kingdoms formed an alliance and pushed them out of India in the 550 AD timeframe.
The Nezak huns settled mainly in present day Afghanistan and Pakistan and kept to themselves mostly. When the Alchon refugees arrived, they were absorbed into the Nezak tribes, possibly through marriage alliances as these coins seem to stress a merging of the two peoples.
The catalyst for this alliance was probably the encroaching Turks, who had conquered most of Central Asia and formed an alliance to defeat the most powerful tribe--the Hepthalites--as retaliation for the defeat of Peroz almost a century earlier. The Nezak-Alchons held out for a time but were ultimately defeated. The Turks remained in power until they were absorbed by the Muslim caliphates.
From my own collection:
Pre-alliance Nezak

Nezak-Alchon

Post-conquest (fire altar attendants replaced with Turk tribal tamgha)
