Ashur-uballit I in the context of "Kassites"

The Middle Assyrian Empire was the third stage of Assyrian history, covering the history of Assyria from the accession of Ashur-uballit I c. 1363 BC and the rise of Assyria as a territorial kingdom to the death of Ashur-dan II in 912 BC. The Middle Assyrian Empire was Assyria's first period of ascendancy as an empire. Though the empire experienced successive periods of expansion and decline, it remained the dominant power of northern Mesopotamia throughout the period. In terms of Assyrian history, the Middle Assyrian period was marked by important social, political and religious developments, including the rising prominence of both the Assyrian king and the Assyrian national deity Ashur.

The Middle Assyrian Empire was founded through Assur, a city-state through most of the preceding Old Assyrian period, and the surrounding territories achieving independence from the Mitanni kingdom. Under Ashur-uballit, Assyria began to expand and assert its place as one of the great powers of the Ancient Near East. This aspiration chiefly came into fruition through the efforts of the kings Adad-nirari I (r. c. 1305–1274 BC), Shalmaneser I (r. c. 1273–1244 BC) and Tukulti-Ninurta I (r. c. 1243–1207 BC), under whom Assyria expanded to for a time become the dominant power in Mesopotamia. The reign of Tukulti-Ninurta I marked the height of the Middle Assyrian Empire and included the subjugation of Babylonia and the foundation of a new capital city, Kar-Tukulti-Ninurta, though it was abandoned after his death. Though Assyria was left largely unscathed by the direct effects of the Late Bronze Age collapse of the 12th century BC, the Middle Assyrian Empire began to experience a significant period of decline roughly at the same time. The assassination of Tukulti-Ninurta I c. 1207 BC led to inter-dynastic conflict and a significant drop in Assyrian power.

Assyria was a major ancient Mesopotamian civilization that existed as a city-state from the 21st century BC to the 14th century BC and eventually expanded into an empire from the 14th century BC to the 7th century BC.

Spanning from the early Bronze Age to the late Iron Age, modern historians typically divide ancient Assyrian history into the Early Assyrian (c. 2600–2025 BC), Old Assyrian (c. 2025–1364 BC), Middle Assyrian (c. 1363–912 BC), Neo-Assyrian (911–609 BC), and post-imperial (609 BC–c. AD 240) periods, based on political events and gradual changes in language. Assur, the first Assyrian capital, was founded c. 2600 BC, but there is no evidence that the city was independent until the collapse of the Third Dynasty of Ur, in the 21st century BC, when a line of independent kings starting with Puzur-Ashur I began ruling the city. Centered in the Assyrian heartland in northern Mesopotamia, Assyrian power fluctuated over time. The city underwent several periods of foreign rule or domination before Assyria rose under Ashur-uballit I in the early 14th century BC as the Middle Assyrian Empire. In the Middle and Neo-Assyrian periods, Assyria was one of the two major Mesopotamian kingdoms, alongside Babylonia in the south, and at times became the dominant power in the ancient Near East. Assyria was at its strongest in the Neo-Assyrian period, when the Assyrian army was the strongest military power in the world and the Assyrians ruled the largest empire then yet assembled in world history, spanning from parts of modern-day Iran in the east to Egypt in the west.

The king of Assyria (Akkadian: Iššiʾak Aššur, later šar māt Aššur) was the ruler of the ancient Mesopotamian kingdom of Assyria, which was founded in the late 21st century BC and fell in the late 7th century BC. For much of its early history, Assyria was little more than a city-state, centered on the city Assur, but from the 14th century BC onwards, Assyria rose under a series of warrior kings to become one of the major political powers of the Ancient Near East, and in its last few centuries it dominated the region as the largest empire the world had seen thus far. Ancient Assyrian history is typically divided into the Old, Middle and Neo-Assyrian periods, all marked by ages of ascendancy and decline.

The ancient Assyrians did not believe that their king was divine himself, but saw their ruler as the vicar of their principal deity, Ashur, and as his chief representative on Earth. In their worldview, Assyria represented a place of order while lands not governed by the Assyrian king (and by extension, the god Ashur) were seen as places of chaos and disorder. As such it was seen as the king's duty to expand the borders of Assyria and bring order and civilization to lands perceived as uncivilized. As Assyria expanded, its rulers gradually adopted grander and more boastful titles. Early kings used Iššiʾak Aššur (representative/viceroy of Ashur), considering the god Ashur to be the true king. From the time of Ashur-uballit I (14th century BC), the rulers instead used king (šar). In time, further titles, such as "king of Sumer and Akkad", "king of the Universe" and "king of the Four Corners of the World", were added, often to assert their control over all of Mesopotamia.

The Old Assyrian period was the second stage of Assyrian history, covering the history of the city of Assur from its rise as an independent city-state under Puzur-Ashur I c. 2025 BC to the foundation of a larger Assyrian territorial state after the accession of Ashur-uballit I c. 1363 BC, which marks the beginning of the succeeding Middle Assyrian period. The Old Assyrian period is marked by the earliest known evidence of the development of a distinct Assyrian culture, separate from that of southern Mesopotamia and was a geopolitically turbulent time when Assur several times fell under the control or suzerainty of foreign kingdoms and empires. The period is also marked with the emergence of a distinct Assyrian dialect of the Akkadian language, a native Assyrian calendar and Assur for a time becoming a prominent site for international trade.

For most of the Old Assyrian period, Assur was a minor city-state with little political and military influence. In contrast to Assyrian kings of later periods, the kings in the Old Assyrian period were just one of the prominent leading officials in the city's administration and normally used the style Išši'ak Aššur, which translates to "governor (on behalf) of (the god) Ashur", rather than šar (king). The kings presided over the city's actual administrative body, the Ālum (city assembly), which was made up of prominent and influential members among Assur's populace. Though lacking in military and political might, Assur was an important economic center in northern Mesopotamia. From the time of Erishum I (c. 1974–1935 BC) until the late 19th century BC, the city was a hub in a large trading network that spanned from the Zagros Mountains in the east to central Anatolia in the west. During their time as prominent traders the Assyrians founded a number of trading colonies at various sites in the trading network, such as Kültepe.

Adad-nīrārī II (also spelled Adad-nērārī, which means "Adad (the storm god) is my help") reigned from 911 BCE to 891 BCE. He was the first King of Assyria in the Neo-Assyrian empire. He instigated the first renewed period of major expansion following that of the Middle Assyrian Empire which had begun in 1365 BCE under Ashur-uballit I and ended after the death of Ashur-bel-kala in 1053 BCE.