Sentence:  "<WSD>Iran</WSD>. in early times, the name applied to the great Asiatic plateau which comprised the entire region from the Caucasus, the Caspian Sea, and Russian Turkestan on the north to the Tigris, the Persian Gulf, and the Arabian Sea on the west and south, and extending to the Indus on the east, likewise comprising the modern Afghanistan and the territory to the north of it as far as the Jaxartes River." 
Meaning of the word marked with <WSD> tags:  regions inhabited by the Iranian peoples.