Ancient Mesopotamia
Main articles: Mesopotamia and History of Mesopotamia
See also: Ancient Near East
Bronze Age
Main articles: Sumer, Akkadian Empire, Assyria, and Babylonia
Sumer emerged as the civilization of Lower Mesopotamia out of the prehistoric Ubaid period (mid-6th millennium BC) in the Early Bronze Age (Uruk period) Classical Sumer ends with the rise of the Akkadian Empire in the 24th century BC. Following the Gutian period, there is a brief Sumerian renaissance in the 21st century, cut short in the 20th century BC by Amorite invasion. The Amorite dynasty of Isin persisted until c. 1600 BC, when southern Mesopotamia was united under Kassite Babylonian rule.

The north of Mesopotamia had become the Akkadian speaking state of Assyria by the late 25th century BC. Along with the rest of Mesopotamia it was ruled by Akkadian kings from the late 24th to mid 22nd centuries BC, after which it once again became independent.

Babylonia was a state in Lower Mesopotamia with Babylon as its capital. It was founded as an independent state by an Amorite king named Sumuabum in 1894 BC.During the 3rd millennium BCE, there developed a very intimate cultural symbiosis between the Sumerians and the Akkadians, which included widespread bilingualism.

Akkadian gradually replaced Sumerian as the spoken language of Mesopotamia somewhere around the turn of the 3rd and the 2nd millennium BC, but Sumerian continued to be used as a written or ceremonial language in Mesopotamia well into the period of classical antiquity.

Babylonia emerged from the Amorite dynasties (c. 1900 BC) when Hammurabi (c. 1792–1750 BC), unified the territories of the former kingdoms of Sumer and Akkad. During the early centuries of what is called the "Amorite period", the most powerful city states were Isin and Larsa, although Shamshi-Adad I came close to uniting the more northern regions around Assur and Mari. One of these Amorite dynasties was established in the city-state of Babylon, which would ultimately take over the others and form the first Babylonian empire, during what is also called the Old Babylonian Period.

Assyria was an Akkadian (East Semitic) kingdom in Upper Mesopotamia, that came to rule regional empires a number of times through history. It was named for its original capital, the ancient city of Assur (Akkadian Aššūrāyu).

Of the early history of the kingdom of Assyria, little is positively known. In the Assyrian King List, the earliest king recorded was Tudiya. He was a contemporary of Ibrium of Ebla who appears to have lived in the late 25th or early 24th century BC, according to the king list. The foundation of the first true urbanised Assyrian monarchy was traditionally ascribed to Ushpia a contemporary of Ishbi-Erra of Isin and Naplanum of Larsa. c. 2030 BC.

Assyria had a period of empire from the 19th to 18th centuries BC. From the 14th to 11th centuries BC Assyria once more became a major power with the rise of the Middle Assyrian Empire.

Iron Age[edit]

The Neo-Assyrian Empire (911–609 BC) was the dominant political force in the Ancient Near East during the Iron Age, eclipsing Babylonia, Egypt, Urartu[9] and Elam. During this period, Aramaic was also made an official language of the empire, alongside the Akkadian language.

The Neo-Babylonian Empire (626 BC–539 BC) marks the final period of the history of the Ancient Near East preceding Persian conquest. A year after the death of the last strong Assyrian ruler, Assurbanipal, in 627 BC, the Assyrian empire spiralled into a series of brutal civil wars. Babylonia rebelled under Nabopolassar, a member of the Chaldean tribe which had migrated from the Levant to south eastern Babylonia in the early 9th century BC. In alliance with the Medes, Persians, Scythians and Cimmerians, they sacked the city of Ninevehin 612 BC, and the seat of empire was transferred to Babylonia for the first time since the death of Hammurabi in the mid 18th century BC. This period witnessed a general improvement in economic life and agricultural production, and a great flourishing of architectural projects, the arts and science. The Neo-Babylonian period ended with the reign of Nabonidus in 539 BC. To the east, the Persians had been growing in strength, and eventually Cyrus the Great established his dominion over Babylon.

Classical Antiquity
Achaemenid and Seleucid rule
Main articles: Babylonia (Persian province), Achaemenid Assyria, and Seleucid Empire
Mesopotamia was conquered by the Achaemenid Persians under Cyrus the Great in 539 BC, and remained under Persian rule for two centuries.

The Persian Empire fell to Alexander of Macedon in 331 BC and came under Greek rule as part of the Seleucid Empire. Babylon declined after the founding of Seleucia on the Tigris, the new Seleucid Empire capital. The Seleucid Empire at the height of its power stretched from the Aegean in the west to India in the east. It was a major center of Hellenistic culture that maintained the preeminence of Greek customs where a Greek political elite dominated, mostly in the urban areas.The Greek population of the cities who formed the dominant elite were reinforced by immigration from Greece. Much of the eastern part of the empire was conquered by the Parthians under Mithridates I of Parthia in the mid-2nd century BC.

Parthian and Roman rule
Main articles: Asuristan, Osroene, Adiabene, Mesopotamia (Roman province), and Assyria (Roman province)
At the beginning of the 2nd century AD, the Romans, led by emperor Trajan, invaded Parthia and conquered Mesopotamia, making it an imperial province. It was returned to the Parthians shortly after by Trajan's successor, Hadrian.

Christianity reached Mesopotamia in the 1st century AD, and Roman Syria in particular became the center of Eastern Rite Christianity and the Syriac literary tradition. Mandeism is also believed to have either originated there around this time or entered as Mandaeans sought refuge from Palestine. Sumerian-Akkadian religious tradition disappeared during this period, as did the last remnants of cuneiform literacy, although temples were still being dedicated to the Assyrian national god Ashur in his home city as late as the 4th century.

Sassanid Empire
Main article: Asuristan
In the 3rd century AD, the Parthians were in turn succeeded by the Sassanid dynasty, which ruled Mesopotamia until the 7th century Islamic invasion. The Sassanids conquered the independent Neo-Assyrian states of Adiabene, Osroene, Hatra and finally Assur during the 3rd century. In the mid-6th century the Persian Empire under the Sassanid dynasty was divided by Khosrow I into four quarters, of which the western one, called Khvārvarān, included most of modern Iraq, and subdivided to provinces of Mishān, Asuristān (Assyria), Adiabene (which was for a time an independent Assyrian state) and Lower Media. The term Iraq is widely used in the medieval Arabic sources for the area in the center and south of the modern republic as a geographic rather than a political term, implying no greater precision of boundaries than the term "Mesopotamia" or, indeed, many of the names of modern states before the 20th century.

There was a substantial influx of Arabs in the Sassanid period. Upper Mesopotamia came to be known as Al-Jazirah in Arabic (meaning "The Island" in reference to the "island" between the Tigris and Euphrates rivers), and Lower Mesopotamia came to be known as ʿIrāq-i ʿArab, meaning "the escarpment of the Arabs" (viz. to the south and east of "the island".

Until 602, the desert frontier of the Persian Empire had been guarded by the Arab Lakhmid kings of Al-Hirah. In that year, Shahanshah Khosrow II Aparviz abolished the Lakhmid kingdom and laid the frontier open to nomad incursions. Farther north, the western quarter was bounded by the Byzantine Empire. The frontier more or less followed the modern Syria-Iraq border and continued northward, passing between Nisibis (modern Nusaybin) as the Sassanian frontier fortress and Dara and Amida (modern Diyarbakır) held by the Byzantines.