What was the name of the region located on the territory of modern Iran?

Persis (Greek: Περσίς, romanized: Persís), better known in English as Persia or Persia proper, is the Fars region, located to the southwest of the modern Iran, now a province. The Persians are thought to have initially migrated either from Central Asia or, more probably, from the north through the Caucasus.

They would then have migrated to the current region of Persis in the early 1st millennium BC. The country name Persia was derived directly from the Old Persian Parsa.