According to the Lonely Planet guide to Iran,

"Most impressive of all, however, and among the most impressive historical sights in all of Iran, are the bas-reliefs of the Apadana Staircase on the eastern wall [of the Apadana Palace]."

"The panels at the southern end [of the Apadana Staircase] are the most interesting, showing 23 delegations bringing their tributes to the Achaemenid king."

"This rich record of the nations of the time ranges from the Ethiopians in the bottom left center, through a climbing pantheon of, among other peoples, Arabs, Thracians, Indians, Parthians and Cappadocians, up to the Elamites and Medians at the top right."

Persepolis, Iran