According to the Book of the Deeds of Ardashir son of Babak, Ardashir I, after having defeated the ParthianArtabanus V, began subduing the vassal-states of the fallen Parthian Empire. With reinforcements from Zavul, he invaded the domains of Madig, but was repelled by the latter. However, Ardashir later returned with an army of 4,000 men, and defeated Madig in a night attack. The Book says the following thing:
He [Ardashir] killed one thousand of the Kurds, (while) others were wounded and taken prisoners; and out of the Kurds (that were imprisoned) he sent to Pars their king with his sons, brothers, children, his abundant wealth and property.
It must be noted though that the usage of the term Kurd during this time period most likely was a social term, designating Iranian nomads, rather than a concrete ethnic group.