Iranian plateau in the context of "Persianization"

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.

Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent. It corresponds roughly to the territory of modern Iraq and forms the eastern geographic boundary of the modern Middle East. Just beyond it lies southwestern Iran, where the region transitions into the Persian plateau, marking the shift from the Arab world to Iran. In the broader sense, the historical region of Mesopotamia also includes parts of present-day Iran (southwest), Turkey (southeast), Syria (northeast), and Kuwait.

Mesopotamia is the site of the earliest developments of the Neolithic Revolution from around 10,000 BC. It has been identified as having "inspired some of the most important developments in human history, including the invention of the wheel, the planting of the first cereal crops, the development of cursive script, mathematics, astronomy, and agriculture". It is recognised as the cradle of some of the world's earliest civilizations.

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.

Greater Iran or Greater Persia (Persian: ایران بزرگ Irān-e Bozorg), also called the Iranosphere or the Persosphere or Iranzamin (Persian: ایران‌زمین Irān-zamin), is a term used to refer to a broader cultural sphere that has been influenced, at least to some degree, by Iranian peoples and Iranian languages, and primarily includes the Iranian plateau, the South Caucasus, Central Asia, the Indian subcontinent, and historically stretched as far east as the Tarim Basin.

The regions which make up Greater Iran are defined by having long been under the rule of various Iranian empires and dynasties, during which the local populace gradually absorbed Iranian influence and assimilated it into their cultural and linguistic traditions; or those where a considerable Iranian population settled and retained their culture, such as in the areas surrounding the Iranian plateau. It is referred to as the "Iranian Cultural Continent" by Encyclopædia Iranica.

The Indo-European languages are a language family native to the northern Indian subcontinent, most of Europe, and the Iranian plateau, with additional native branches found in regions such as parts of Central Asia (e.g., Tajikistan and Afghanistan), southern Indian subcontinent (Sri Lanka and the Maldives) and Armenia. Historically, Indo-European languages were also spoken in Anatolia and Northwestern China. Some European languages of this family—English, French, Portuguese, Italian, Russian, Spanish, and Dutch—have expanded through colonialism in the modern period and are now spoken across several continents. The Indo-European family is divided into several branches or sub-families, including Albanian, Armenian, Balto-Slavic, Celtic, Germanic, Hellenic, Indo-Iranian, and Italic, all of which contain present-day living languages, as well as many more extinct branches.

Today the individual Indo-European languages with the most native speakers are English, Spanish, Portuguese, Russian, Hindustani, Bengali, Punjabi, French, and German; many others spoken by smaller groups are in danger of extinction. Over 3.4 billion people (42% of the global population) speak an Indo-European language as a first language—by far the most of any language family. There are about 446 living Indo-European languages, according to an estimate by Ethnologue, of which 313 belong to the Indo-Iranian branch.

The Mongol Empire was the largest contiguous empire in history. Originating in present-day Mongolia in East Asia, the empire at its height stretched from the Sea of Japan to Eastern Europe, extending northward into Siberia and east and southward into the Indian subcontinent, mounting invasions of Southeast Asia, and conquering the Iranian plateau; and reaching westward as far as the Levant and the Carpathian Mountains.

The empire emerged from the unification of several nomadic tribes in the Mongol heartland under the leadership of Temüjin, known by the title of Genghis Khan (c. 1162–1227), whom a council proclaimed as the ruler of all Mongols in 1206. The empire grew rapidly under his rule and that of his descendants, who sent out invading armies in every direction. The vast transcontinental empire connected the East with the West, and the Pacific to the Mediterranean, in an enforced Pax Mongolica, allowing the exchange of trade, technologies, commodities, and ideologies across Eurasia.

The History of Iran (also known as Persia) is intertwined with Greater Iran, which is a region encompassing all of the areas that have witnessed significant settlement or influence by the Iranian peoples and the Iranian languages – chiefly the Persians and the Persian language. Central to this region is the Iranian plateau, now largely covered by modern Iran. The most pronounced impact of Iranian history can be seen stretching from Anatolia in the west to the Indus Valley in the east, including the Levant, Mesopotamia, the Caucasus, and parts of Central Asia. It also overlaps or mingles with the histories of many other major civilizations, such as India, China, Greece, Rome, and Egypt.

Iran is home to one of the world's oldest continuous major civilizations, with historical and urban settlements dating back to the 5th millennium BC. The Iranian plateau's western regions integrated into the rest of the ancient Near East with the Elamites (in Ilam and Khuzestan), the Kassites (in Kuhdesht), the Gutians (in Luristan), and later with other peoples like the Urartians (in Oshnavieh and Sardasht) near Lake Urmia and the Mannaeans (in Piranshahr, Saqqez and Bukan) in Kurdistan. German philosopher Georg Wilhelm Friedrich Hegel called the Persians the "first Historical People" in his Lectures on the Philosophy of World History. The sustained Iranian empire is understood to have begun with the rise of the Medes during the Iron Age, when Iran was unified as a nation under the Median kingdom in the 7th century BC. By 550 BC, the Medes were sidelined by the conquests of Cyrus the Great, who brought the Persians to power with the establishment of the Achaemenid Empire. Cyrus' ensuing campaigns enabled the Persian realm's expansion across most of West Asia and much of Central Asia, and his successors would eventually conquer parts of Southeast Europe and North Africa to preside over the largest empire the world had yet seen. In the 4th century BC, the Achaemenid Empire was conquered by the Macedonian Empire of Alexander the Great, whose death led to the establishment of the Seleucid Empire over the bulk of former Achaemenid territory. In the following century, Greek rule of the Iranian plateau came to an end with the rise of the Parthian Empire, which also conquered large parts of the Seleucids' Anatolian, Mesopotamian, and Central Asian holdings. While the Parthians were succeeded by the Sasanian Empire in the 2nd century, Iran remained a leading power for the next millennium, although the majority of this period was marked by the Roman–Persian Wars.

Media (Old Persian: 𐎶𐎠𐎭 Māda; Greek: Μηδία Mēdía; Akkadian: Mādāya) was a political entity centered in Ecbatana that existed from the 7th century BCE until the mid-6th century BCE and is believed to have dominated a significant portion of the Iranian plateau, preceding the powerful Achaemenid Empire. The frequent interference of the Assyrians in the Zagros region led to the process of unifying the Median tribes. By 612 BCE, the Medes became strong enough to overthrow the declining Assyrian empire in alliance with the Babylonians. However, contemporary scholarship tends to be skeptical about the existence of a united Median kingdom or state, at least for most of the 7th century BCE.

According to classical historiography, Media emerged as one major power of the ancient Near East after the collapse of Assyria. Under Cyaxares (r. 625–585 BCE), the kingdom's borders were expanded to the east and west through the subjugation of neighboring peoples, such as the Persians and Armenians. Media's territorial expansion led to the formation of the first Iranian empire, which at its height would have exercised authority over more than two million square kilometers, stretching from the eastern banks of the Halys River in Anatolia to Central Asia. In this period, the Median empire was one of the great powers in the ancient Near East alongside Babylon, Lydia, and Egypt. During his reign, Astyages (r. 585–550 BCE) worked to strengthen and centralize the Median state, going against the will of tribal nobility, which may have contributed to the kingdom's downfall. In 550 BCE, the Median capital, Ecbatana, was conquered by the Persian king Cyrus II, marking the beginning of the Achaemenid empire.