Persis in the context of "Mithridates I of Parthia"

The Achaemenid Empire (/əˈkiːmənɪd/ ə-KEE-mə-nid; Old Persian: 𐎧𐏁𐏂, Xšāça, lit. 'The Empire' or 'The Kingdom') was an ancient Iranian empire founded by Cyrus the Great of the Achaemenid dynasty in 550 BC. At peak, its territorial extent was roughly 5.5 million square kilometres (2.1 million square miles), making it the largest empire of its time. Based in the Iranian plateau, it stretched from the Balkans and Egypt in the west to the Indus Valley in the east, including Anatolia, Cyprus, Mesopotamia, the Levant, parts of Eastern Arabia, and large parts of Central Asia.

By the 7th century BC, the region of Persis, located in the southwestern part of the Iranian plateau, had been settled by Persians. From Persis, Cyrus rose and defeated Media, Lydia, and the Neo-Babylonian Empire, thus marking the establishment of a new imperial polity in the ancient Near East. While its conquests were largely successful in most regions, the Achaemenid Empire's attempts to expand into Greece proved extremely difficult over the course of decades of wars and multiple kings, ultimately resulting in its defeat in the Greek mainland.

Persians, or the Persian people, are an Iranian ethnic group from West Asia. They are indigenous to the Iranian plateau and comprise the majority of the population of Iran. They have a common cultural system and are native speakers of the Persian language. In the Western world, "Persian" was largely understood as a demonym for all Iranians rather than as an ethnonym for the Persian people, but this understanding shifted in the 20th century.

The Persians were originally an ancient Iranian people who had migrated to Persis (also called "Persia proper" and corresponding with Iran's Fars Province) by the 9th century BCE. Together with their compatriots, they established and ruled some of the world's most powerful empires, which are well-recognized for their massive cultural, political, and social influence in the ancient Near East and beyond. The Persian people have contributed greatly to art and science, and Persian literature is one of the world's most prominent literary traditions both inside and outside of Iran. The regional prestige of their civilization was the basis for the development of many noteworthy Persianate societies, especially among the Turkic peoples, throughout Central Asia and South Asia.

Cyrus II of Persia (c. 600 – 530 BC), commonly known as Cyrus the Great, was the founder of the Achaemenid Empire. Hailing from Persis, he brought the Achaemenid dynasty to power by defeating the Median Empire and embracing all of the previous civilized states of the ancient Near East, expanding vastly across most of West Asia and much of Central Asia to create what would soon become the largest empire in history at the time. The Achaemenid Empire's greatest territorial extent was achieved under Darius the Great, whose rule stretched from Southeast Europe in the west to the Indus Valley in the east.

After absorbing the Median Empire, Cyrus conquered Lydia and eventually the Neo-Babylonian Empire, granting him control of Anatolia and the Fertile Crescent, respectively. He also led a major expedition into Central Asia, where his army brought "into subjection every nation without exception" before he allegedly died in battle with the Massagetae, a nomadic Eastern Iranian people, along the Syr Darya in December 530 BC. However, according to Xenophon of Athens, Cyrus did not die fighting and had instead returned to the capital city of Pasargadae. Regardless of the date of his death, he was succeeded by his son Cambyses II, whose campaigns into North Africa led to the conquests of Egypt, Nubia, and Cyrenaica during his short rule.

The Iranian plateau or Persian plateau is a geological feature spanning parts of the Caucasus, Central Asia, South Asia, and West Asia. It makes up part of the Eurasian plate, and is wedged between the Arabian plate and the Indian plate. The plateau is situated between the Zagros Mountains to the west, the Caspian Sea and the Köpet Dag to the north, the Armenian Highlands and the Caucasus Mountains to the northwest, the Strait of Hormuz and the Persian Gulf to the south, and the Indian subcontinent to the southeast.

As a historical region, it includes Parthia, Media, Persis, and some of the previous territories of Greater Iran. The Zagros form the plateau's western boundary, and its eastern slopes may also be included in the term. The Encyclopædia Britannica excludes "lowland Khuzestan" explicitly and characterizes Elam as spanning "the region from the Mesopotamian plain to the Iranian Plateau".

Persian, also known by its endonym Farsi or Parsi, is a Western Iranian language belonging to the Iranian branch of the Indo-Iranian subdivision of the Indo-European languages. Persian is a pluricentric language predominantly spoken and used officially within Iran, Afghanistan, and Tajikistan in three mutually intelligible standard varieties, respectively Iranian Persian (officially known as Persian), Dari Persian (officially known as Dari since 1964), and Tajiki Persian (officially known as Tajik since 1999). It is also spoken natively in the Tajik variety by a significant population within Uzbekistan, as well as within other regions with a Persianate history in the cultural sphere of Greater Iran. It is written officially within Iran and Afghanistan in the Persian alphabet, a derivative of the Arabic script, and within Tajikistan in the Tajik alphabet, a derivative of the Cyrillic script.

Modern Persian is a continuation of Middle Persian, an official language of the Sasanian Empire (224–651 CE), itself a continuation of Old Persian, which was used in the Achaemenid Empire (550–330 BCE). It originated in the region of Fars (Persia) in southwestern Iran. Its grammar is similar to that of many European languages.

Fars Province, in Persian Ostâne Fârs, historically known outside of Iran as Persia proper, is one of the 31 provinces of Iran. Its capital is the city of Shiraz.

Pars province has an area of 122,400 km and is located in Iran's southwest, in Region 2. It neighbours the provinces of Bushehr to the west, Hormozgan to the south, Kerman and Yazd to the east, Isfahan to the north, and Kohgiluyeh and Boyer-Ahmad to the northwest.