The Assyrian Empire, which existed in the Near East from approximately the 25th century BCE to its collapse around 600 BCE, was historically significant in part because it conquered Mesopotamia and much of the Near East and spread its language, such as Aramaic, and culture throughout its empire. The empire spread out from the city of Ashur, a trading center, and part of its significance came from the sophistication of the banking system that was used in Ashur and that helped it grow in wealth. In this system, independent investors put capital in the merchants' trade with Anatolia for a return on the profits. 

Another reason the Assyrians were significant is that their army was powerful. The army developed iron weapons from the Assyrian trade for raw materials with Anatolia. The Assyrians were able to conquer neighboring tribes such as the Mittani and Hittites and to establish order, law, and prosperity in these new territories with their large bureaucracy. Under the period of Tiglath Pileser I (c. 1115-1076 BCE), the Assyrians recovered from a period of stasis to go on to conquer new lands, build a new library and palace in the capital city, establish laws known as the Middle Assyrian Laws, and construct fine gardens. Tiglath Pileser emphasized the importance of literacy--a tradition later continued by Ashurbanipal, who constructed a library at Nineveh with more than 30,000 cuneiform tablets. The Assyrians also had many mathematical and scientific achievements, such as the invention of longitude and latitude in navigation and the improvement of medical science. Their architectural, scientific, and cultural achievements; military prowess; and laws contribute to the Assyrians' historical significance, as does their longevity in the ancient world. 

Although the Assyrian Empire is not as well known or as popular as empires like that of Egypt, it is still quite important historically.

The Assyrian Empire was the first real empire to exist in the world.  It spread civilization across a large area of the world through its conquests.  This, on its own, would make it significant.  The Assyrians also gave the world a number of innovations.  This was the first large army to be equipped with iron weapons.  It was also the source of a number of culturally important things.  For example, Assyrian gods and Assyrian legends became very influential in the surrounding area.  Perhaps the most important example of this is the Epic of Gilgamesh, which may well have helped to influence the Old Testament.

The Assyrians, then, spread their civilization across the Near East, laying a foundation for the culture of the area from which the Judaeo-Christian tradition arose.