Apadana tribute reliefs

The tribute reliefs from the East staircase of the Apadana at Persepolis (identical reliefs also on the North staircase).  Delegations of 23 different peoples are represented; their identification is not always certain. Each delegation is preceded by an 'usher' in Persian dress, who holds the hand of the leader of the delegation and leads him towards the king (represented in the centre of the staircase in the 'audience relief').  The delegates of the various subject peoples are ethnically distinguished by dress and hair-styling; each delegation brings culturally specific gifts of various kinds (animals, garments, vessels).   

Excellent photographs can be found in G. Walser, Die Völkerschaften auf den Reliefs von Persepolis (1966), and on the website of the Chicago Oriental Institute, here.  See also (briefly) Briant, From Cyrus to Alexander 174-7; at greater length, M. Cool Root, The King and Kingship in Achaemenid Art (1979), 227-284.

For an illuminating parallel passage (Herodotus 7.61ff), see A. Kuhrt, The Persian Empire: A Corpus of Sources from the Achaemenid Period (2007), 519-29 (illustrated with Apadana tribute reliefs).