We first hear of the Assyrians around 2300 BC, when Sargon of Akkad invaded their small kingdom to the north. After 2000 BC, when Assur became independent of the collapsing 3rd Dynasty of Ur, the Assyrians became well-known traders, who travelled constantly
between Assur and southern Turkey with their donkeys, carrying cloth from Assur and tin from beyond the Tigris to the east, and trading it in southern Turkey for gold, silver, and other metals. But
as the Hittites took over Turkey around 1800 BC, this trade gradually collapsed. The last Assyrian caravan to Turkey was ca. 1780 BC.
Desert in Iraq (Assur)
By 1700 BC the Assyrians had been conquered by the Amorites, and later they were controlled by the Hurrians for a long time. But when the Hurrian kingdom collapsed about 1360 BC, the Assyrian governor of Assur, whose name was Assur-uballit, saw his chance and began calling himself the King of Assyria. Assur-uballit and the Assyrians soon had to fight both the Hurrians and the Kassites in order to stay independent, but they won their wars and were able to establish themselves. They made a lot of alliances with the Kassites to their south, with many Assyrian princesses marrying Kassite princes and vice versa.
Under their king Tukulti-Ninurta I (known in the book of Genesis as Nimrod), about 1225 BC, the Assyrians conquered the Kassites and the city of Babylon, capturing the great statue of the god Marduk there and bringing it back to Assur. But people objected to this sacrilege, and the conquest of Babylon, and a mob led by his son burned Tukulti-Ninurta to death by setting fire to his palace, and freed the Kassites again. A Dark Age overtook West Asia about this time, with the invasions of the Sea Peoples and a lot of movement among the Hittites, the Hurrians, and the Jews, and the gradual collapse of the Kassites as a result.
The Assyrian king
The Assyrians were the only big kingdom in West Asia not to collapse as a result of the Dark Ages, and so they were in a good position to take over afterward. By 1115 BC, under their king Tiglath-pileser I, they were able to expand south into Babylonia again (being more careful to respect the ancient gods there this time), and west. At first, these were basically plundering expeditions. The Assyrian army, which was feared everywhere, started out pretty much every spring going south along the Tigris river, and then cross to the Euphrates and follow that upstream until it got home again to Assur, around the end of the summer.
Along the way the soldiers collected whatever took their fancy: cloth, gold, artwork, or slaves. Assyrian inscriptions call this "tribute", but people either gave it in order to keep from being attacked, or the Assyrian soldiers attacked them
and took it anyway. These plundering expeditions continued more or less every year for hundreds of years, down to Assurnasirpal's reign in the 800s BC.
Assurnasirpal's son Shalmaneser III decided to expand the Assyrian empire even more. He took the plundering expeditions even further west, where he first met the Jewish kingdoms of Israel and Judah. At first they resisted him successfully, but by the 830s Shalmaneser seems to have placed pro-Assyrian Jews on the thrones of both kingdoms, and we guess that he collected tribute as well.