The Middle Assyrian Period (1365 - 1077 BC) is marked by growth of Assyrian power.
By the Middle Assyrian Period, the Kassite Dynasty usurped Babylonia, the Hittites settled in Anatolia and the Mitanni ruled northern Mesopotamia. The core of Assyria was a vassal within the larger Mitanni state. The Middle Assyrian Period begins with attacks against the Mitanni by the Hittite king Suppiluliumas, weakening the Mitanni enough to allow Assyria to regain independence.
Ashur-uballit I (1363-1328 BC) is considered the first true king of Assyria. He transformed a peaceful merchant state into a kingdom with its capital at Ashur. During the Middle Assyrian Period, Babylonia exerted a huge cultural influence on Assyria. Enlil, a supreme Babylonian god paralleled in Assyria by the god Ashur, rose to prominence in Assyria. Adad-narari and his son Shalmaneser I both gave themselves the primary title governor of the god Enlil. Also, a Babylonian dialect (not Assyrian) was used for the Assyrian royal inscriptions which became numerous from the time of Shalmaneser I.
Ashur-uballit I established permanent control over northern Iraq, incorporated main cities of the region and added important agricultural ties to the north and east. He tried to establish Assyria as a powerful kingdom amidst Egypt and Babylonia.
Enlil-nirari I's grandson described him as the one who widened borders and boundaries, indicated that Enlil-nirari I attempted to continue Ashur-uballit's successes. At one point, Enlil-nirari is labeled the one who slew the hosts of the Kassites, referring to Babylon's occupation by Kassites since ~1,600 BC and to Enlil-nirari's response to Babylon's failed attempt to make a vassal out of Assyria.
Arik-den-ili extended Assyrian borders for both expansionism and survival. An enemy from the Taurus foothills had reached just north of Nineveh, threatening Assyria's heartland. Arik-den-ili not only defeated this advance, but penetrated the eastern Taurus (fighting the Qutians who dwelt there) and also advanced northwest to capture the Kadmukh plains that were west of the Tigris and bound by the Tur Abdin plateau.
Notably, up until this point, a pious Assyrian viewed the god Ashur as king; the ruler was merely his human representative. Thus, rulers were described as governors, overseers and supreme judgees. An Assyrian ruler only referred to himself as king when writing a letter, as did Ashur-uballit I. Arik-den ili, boldly departed from this tradition and asserted himself as mighty king, king of Assyria in formal inscriptions for the gods. Adad-narari up-stepped his father and referred to himself as king of the universe.
Adad-nirari I (aka Adad-narari I) annexed the Mitanni, but lost large parts of Mesopotamia to the Hittites. Regardless, Assyria now controlled the western and northern territories with the boundaries of the Euphrates and Tigris. Assyria now controlled the whole western and northern territory within the defensible boundaries of the Euphrates and Tigris, giving Assyria hegemony over the riverine trade routes. To the south, just east of the Tigris, the boundary between Assyria and Babylonia was formed by either the Lower Zab, Adhaim or Diyala rivers. Adad-narari's hard stance on this boundary led to celebratory epic, one of Assyria's first native literary works. However, this area was battled over innumerable times and fluctuated according to levels of Assyro-Babylnonian power.
Shalmaneser I re-conquered territories, but rather just killing the occupants he implemented an Assyrian administration across upper Mesopotamia and possibly the upper Tigris. Other novel policies of Shalmaneser I including adopting established merchants into a profitable Assyrian trading network, and deporting all others to serve as field labors in Assyria. Also, Shalmaneser I did his best to destroy the Urartian chiefdoms before they could pose a significant threat to Assyrian hegemony.
Tukulti-Ninurta I, Shalmaneser I's son, first charged north to regain control of the rebellious barbarians in the northern mountains. He cemented Assyria's control there and set up garrisons, but in a departure from prior policy he allowed merchant families to live. He adapted their trade infrastructure to Assyria's benefit. Next, Tukulti-Ninurta I campaigned southward, invading and conquering Babylonia. This had a profound influence on Assyrian culture, as Babylonians, their gods and their customs swept across Assyria.
Tukulti-Ninurta I was the first Assyrian king to move the capital when he shifted the center of government to Kar-Tukulti-Ninurta. This was not only a strategic move, but also a way to mark his reign. However, when Babylonia's Nebuchadnezzer I successfully revolted, Tukulti-Ninurta I's claim of divine approval was discredited and he was thought of as an evil man who had cast destruction upon Babylonia. His son Ashur-nasir-pal and the nobles of Ashur rebelled by removing him from his throne, imprisoning him and then killing him.
Assyrian Recension (1,207 - 1,116 BC)
Assyrian inscriptions for the next several reigns are very scarce. As inscriptions usually commemorate a king's accomplishments to gain credit with the gods, this indicates that Assyria was relatively weak and inactive. This arose due to instability after Tukulti-Ninurta I's reign, as evidenced by a series of relatively short reigns. In the ancient Near East, the public's rare opportunity to make its opinion known is only after a king's death. Thus, it is likely that revolts, disturbances and rival prince-led factions struggled for control.
Meanwhile, elsewhere, the Elamite empire rose under Shutruk Nahhunte (1157 BC), Kutir Nahhunte (1155 BC) and Shilhak-Inshushinak (1132-1127 BC).. By the middle of the 12th century BC, it was Elam in southwest Iran (Khuzistan) that was the dominant power (not Assyria nor Babylonia). Also, migrations in the eastern Mediterranean had precipitated the collapse of the Hittite empire and attempts at settlement along the Levant coast. Babylonia's Second Dynasty of Isin began under Nebuchadnezzar I (1125-1105 BC). The Assyrian Recension ended with the reign of Tiglath-Pileser I.
The Tigris changed its course at Ashur during Ashur-nadi-apli's reign, but fortunately returned to its prior bed due to royal prayers (and help from Assyrian engineers).
With Babylonian support, Ninurta-apil-Ekur usurped the Assyrian throne. This allowed renewed economic stability, giving his son Ashur-dad I the longest reign in Assyrian history.
Despite reigning longer than any other Assyrian king, Ashur-dad I's inscriptions are scarce. There was a minor, local and typical Assyro-Babylonian border clash.
Ashur-rosha-ishi I (aka Ashur-resh-ishi I) precipitated the Assyrian Renewal brought by his son, Tiglath-Pileser I. He embarked on consolidation campaigns in regions north and east that were under Assyrian, and also made infrastructure improvements after a damaging earthquake earlier in the century.
Nascent Assyrian Empire
Ashur suffered during the Late Bronze Age collapse and incurred territorial losses, but kings of Ashur remain control between the Tigris and the mountain barriers. Its political system remained stable and, interestingly, it never lost its chariot troops. This means it was able to socially and financially maintain this highly specialized and effective branch of its armed forces. This meant the kingdom of Ashur had a military advantage when territorial expansion began at the end of the 10th century BC with the rise of the Neo-Assyrian Empire.
Tiglath-pileser I sets the tone for the rest of the Assyrian empire. He was listened to because he presented himself as a direct pipeline to the gods. Tiglath-pileser I (1115 to 1077 BC) restored lands east of hte Euphrates. Crossed the Euphrates 28 times chasing the Aramaeans, according to his inscriptions. Reached Van Area and carved his image on the Tigris Tunnel north of Diyarbakir. Marched to the Mediterranean. The eocnomic concern of Tiglath-Pileser I is specifically mentioned in his inscriptions that he built up grain store, and increased herds.
Tiglath Pileser I restores lands east of Euphrates, campaigns in the Van area and leaves his image on a rock. Marches to the Mediterranean (Byblos and Sidon do hommage, went for a sail, caught a large fish, builds a cedar roof for the temple of Anu and Adad). Organizes deeds chronologically -- the birth of the Assyrian Annals. As a good tourist he just wanted to honor the gods, knowing the Epic of Gilgamesh where one of the things is to go to the legendary cedar forest and bring back the trees, he does the same things and then builds the nice roof.
Tiglath-Pileser ended his military exploit description in he annals with a count of the wild animals (lions, bulls and elephats) he had hunted and killed. This reflects the heroic nature of the king, and is followed by the protective descriptins of his building activities. There is stress on his divine selection as aking and hsi blessedness, and that he did not enrichhimself with his spoils but honored and exalted the gods.
Brother of Ashur-bel-kala I, son of Tiglath-Pileser I.
Ashur-bel-kala I (son of Tiglath-Pileser I) took immediate action in the north upon ascending the throne, but his government was too weak to implement an Assyrian administration there. Assyrian power rapidly declined due to the loose, growing population of Aramaean tribes. Despite being plundered endlessly by the Assyrians, the Aramaeans were too pervasive to be simply pushed back across the Euphrates. The Ashur-bel-kala I allied with the Babylonian king Marduk-shapik-zeri to fight their mutual problem with the Aramaeans. Upon the usurp of the Babylonian throne by an Aramaean, however, Ashur-bel-kala I chose to simply ally with the Aramaeans and treat them as vassals. This backfired when Ashur-bel-kala I's son (and successor) was removed from the throne by his uncle Shamshi-Adad IV (another on of Tiglath-Pileser I), who had Babylonian support.
Begin with Shamshi-Adad IV, there was a century of Assyrian instability and decentralization.
Then under Tiglath-Pileser II (966-935) there was chaos due to prolonged drought, Aramaeans in the heart of Assyria and Sea Peoples in West.