A Michael Wood documentary for BBC and PBS
Ancient Iranian people or "Iranic people" were made up of various tribes, some of these tribes were the Persians, Medes, Scythians, Parthians, Bactrians, Alans, Cimmerians, and Sarmatians.
The Persians, Medes, Parthians were nomadic tribes that settled down and populated the Iranian Plateau, Zargos Mountains and the Bactrians settled parts of what is now Afghanistan. Alans, Cimmerians, Sarmatians and other Scythian tribes were nomadic horse riding warrior cultures who populated the vast Steppes (prairies) North of the Black and Caspian Seas in what is now Ukraine, Russia, and Kazakhstan.
"Iranian people" belong to the Proto-Indo-European (PIE) community which is ancestral to the Celtic, Latin, Spanish, Romanian, French, Germanic, Baltic, Slavic, Indo-Iranian, Albanian, Armernian, Greek, and Tocharian languages.
There is an agreement that the PIE community split into 2 major groups. One headed west into Europe and became speakers of Indo-European (all the languages of modern Europe except for Basque, Hungarian, and Finnish) while others headed South to become Indo-Iranians.
The Indo-Iranians were a community that spoke a common language prior to their branching off into the Iranian and Indo-Aryan languages. Iranian refers to the languages of Iran (Persian, Laki, Gilaki, Luri etc. ), Pakistan (Baluch), Afghanistan (Pashto), Tadjikistan (Tadjik) etc. and Indo-Aryan: Sanskrit, Hindi and its many related languages.
During the Bronze Ages the settled Iranian tribes, gave birth to various kngdoms and empires and some of the Iranian nomadic horse riding warrior cultures developed a manufacturing and trading civilization, probably originating in the Ural River Valley, while retaining a partial nomadic lifestyle.. This was the start of long distance trade and large scale manufacturing, producing bronze weapons, cooking utensils, and tools which were traded for furs, metal ores, gemstones and other goods over long distances by cargo wagons with wooden spoke wheels much like the American covered wagon. The first salespeople and long distance trade on a large scale begins.