This is one of the 23 delegations (satrapies) shown bringing offerings to the King during the New Year (Nou Rutz) festival.
The bas relief of each delegation provides valuable insight into the clothes and gifts from each region at that time.

The Assyrian delegation are 4th from the left on the middle tier of the Apadana stairway.
They are represented by 8 members, and bring vessels, clothing, a lamb's skin and 2 rams.
The Assyrians came from a region centered on the Upper Tigris river, in northern Mesopotamia. The Assyrian empire was itself powerful at various times.

The original bas relief is shown in one of the photographs (with low tonal range due to the shade).
The other photographs have been digitally enhanced by blurring the background in order to reveal their otherwise hidden beauty.
I hope you find them as fascinating as I do.