The Persian people are part of the Iranian peoples who speak the modern Persian language and closely akin Iranian dialects and languages. The origin of the ethnic Iranian/Persian peoples are traced to the Ancient Iranian peoples, who were part of the ancient Indo-Iranians. The synonymous usage of Iranian and Persian has persisted over the centuries although some modern Western sources use Iranic/Iranian as a wider term that includes the term Persian as well as related Iranian languages and ethnic groups. However, these terms have been used both synonymously as well as in a complementary fashion since ancient times; as the Ancient Iranian peoples such as the Old Persians, Medes, Bactrians, Parthians and Avesta peoples considered themselves to be part of the greater Iranian ethnic stock.

The term Persian translates to "from or of Persis" which is a region north of the Persian Gulf located in Pars, Iran. It was from this region that Cyrus the Great, the founder of the Achaemenid empire, united all other Iranian empires (such as the Medes and the Elamites), and expanded the Persian cultural and social influences by incorporating the Babylonian empire, and the Lydian empire. Although not the first Iranian empire, the Achaemenid empire is the first Persian empire well recognized by Greek and Persian historians for its massive cultural, military and social influences going as far as Athens, Egypt, and Libya.

Cyrus II of Persia (Old Persian: Kuruš (c. 600 BC or 576 BC–530 BC), commonly known as Cyrus the Great, also known as Cyrus the Elder, was the founder of the Achaemenid Empire. Under his rule, the empire embraced all the previous civilized states of the ancient Near East, expanded vastly and eventually conquered most of Southwest Asia and much of Central Asia, parts of Europe and the Caucasus. From the Mediterranean sea and Hellespont in the west to the Indus River in the east, Cyrus the Great created the largest empire the world had yet seen. He also pronounced one of the first historically important declarations of human rights via the Cyrus Cylinder sometime between 539-530 BCE.

The reign of Cyrus the Great lasted between 29 and 31 years. Cyrus built his empire by conquering first the Median Empire, then the Lydian Empire and eventually the Neo-Babylonian Empire. Either before or after Babylon, he led an expedition into central Asia, which resulted in major campaigns that were described as having brought "into subjection every nation without exception". Cyrus did not venture into Egypt, as he himself died in battle, fighting the Massagetae along the Syr Darya in December 530 BC. He was succeeded by his son, Cambyses II, who managed to add to the empire by conquering Egypt, Nubia, and Cyrenaica during his short rule.