The Assyrians managed an extensive trade network during the Old Assyria era, from about 2000 to the end of the Old Assyrian era around 1600 BC.
In the Old Assyrian period, it was typical for Assyrian men to live part- or full-time at an Anatolian merchant colony called a karum Leick 2001, p 202. The merchant brought goods from Assyria, typically textiles produced at his estate by his wife and other household females. These exports which were sold at a premium to the Anatolians. Sheet-like cloth was the bulk of the trade, but Anatolian elites eagerly paid high prices for ornate textiles. The female producers were compensated with a profit share.
Assyrian pre-history (including part of the Old Assyrian Period) is covered by the Assyrian Kinglist. Ashur has little evidence on early Assyria, but karum Kanesh (modern Kültepe) has yielded ~14,000 tablets so far. These tablets date to the dawn of the 2nd millennium. (The greater Cappadocia region hosted merchants as early as the 24th century BC.) These tablets revealed that Ashur's businesses organized trade by placing representatives in multiple cities.
Copper-hungry Assyria expanded commercially into copper-rich Anatolia, both importing copper and feeding tin (from the east) and textiles (from Babylonia) into Anatolia. This system benefited the foreigners (their rulers allowed their existence) and also Assyria (which needed vital timber and metals).
Merchants grouped together in large convoys, evidenced by some documents mentioning only a single donkey. It was too unsafe to take a single donkey alone for a 2 month, ~750 mile and sometimes deadly route. There were outposts of Assyrian merchants along the way to facilitate transport. A donkey's total load, including harness was ~100 kilos. Tin was usually carried in a pair of balanced bullas. Textiles were rolled and placed on top of the donkey.
These ass caravans would set off for Anatolia, along with documentation which was inspected against the load.
Upon arrival at Kanesh, the loads were processed and taxed before they could be resold. This suggests a system of private capitalists, rather than government workers.
Taxes were hefty -- in addition to Kanesh's tax, 10% of the load's value en route -- and smuggling sometimes occurred. Sales often used gold and silver, but textiles and copper intermediaries were oft used and then resold for precious metals. Gross profits of as much as 100% were typical on tin, and textiles could garner even more.
Principals in Anatolia would send the earnings back to their colleague in Ashur (sometimes a wife), and more goods were purchased for shipment to Anatolia. Even if they had a wife in Ashur, principals would sometimes be abroad for years and take additional wives.
The Old Period's last two rulers, Shamshi-Adad I and Ishme-Dagan, had hegemony all the way to the western Zagros (a region between the Euphrates and Tigris).
After Ishme Dagan, king Hammurabi (~1,770-1,650 BC) of Old Babylon slaughtered the Assyrian king and turned Assyria into a vassal. However, trade activity continued and Ashur remained a link between Iran (tin), Mesopotamia and Anatolia (copper). Assyria still made large profits on tin and prized textiles.
Spans 1900 BC
Documents in Anatolia mark the dawn of expansive Assyrian trade to ~1,900 BC. This matches Kanesh texts that mark Erushim I as the first Assyrian ruler. However, the massive trade infrastructure had likely been built upon by prior Assyrian rulers.
Assyria had not been directly affected by Amorites until the Amorite king Shamshi-Adad I extended from Ekallatum to take Ashur and continue to unify much of northern Mesopotamia. Thus was born one of the great territorial states of the early second millennium (early Bronze Age of Mesopotamia), along with Hammurabi's Babylon and Hattusili's Central Anatolia. However, the state created by Shamshi-Adad collapsed soon after his death and Assyrian hegemony retreated to Ekallatum (his homeland) and Assur -- for the rest of Assyrian history until its final collapse, this nucleus of Assyrian control would remain intact.
Shamshi-Adad's son Ishme-Dagan ruled for forty years, but quickly lost control of the middle Euphrates, northeast Syria and even Shubat-Enlil; Ishme-Dagan ruled only Assyria's core region based in Ashur, Nineveh, Erbil and possibly Arrapkha (Kirkuk).
Assyria was insignificant under Mittannian suzerainty, which spanned about 6 Assyrian reigns and from the Zagros to the Kirkuk. Until ~1,420 BC there were not even any extant Assyrian royal inscriptions, although Assyrian kings retained their impotent title. Assyrian legal texts from the 15th century BC mention Hurrian officials, and two later officials even left monuments indicating their Hurrian heritage. In ~1,360 BC, Ashur-uballit wrote as though he was even a descendant of a Hanigalbat king. Saustatar looted Ashur of a door of silver and gold, using it in his own palace at Washukanni.
The primary source of information for this period is from archives at Nuzi, a site in the Kirkuk region. Even before Assyria's vassaldom, this region had existed as a sub-kingdom of Assyria with a modicum of independence. During hegemony by Mittanni, though, the entire Kirkuk region was filled with Hanigalbatian settlers, messengers, officials and military units.
End of Hurrian Rule
Toward end of the 15th century, Ashur had regained enough strength to rebuild its walls, form a boundary treaty with Babylonia and even merit a gold present from Egypt. When the Hittites allied with the Hurri to fight the Mittanni, the Mittanni kingdom was destabilized and Assyria (like under Eriba-Adad's rule) and Alshe (another kingdom) both seized Mittannian territory. Assyria's removal of Mittanian shackles was exemplified by Ashur-uballit's letter directly to Egyptian pharaoh just after ~, where he addressed the pharaoh as my brother. Babylonia's king was less than thrilled as his fantasies of ruling Assyria grew unrealistic: "Why have these Assyrians, who are my subjects...come to your country? If you love me, do not let them get what they want. Send them off empty-handed."
Father of Ashur-uballit