"At approximately 2200 BC, occupations of Tell Leilan and Tell Brak (in northern Mesopotamia) were suddenly abandoned...a marked increase in aridity and wind circulation, subsequent to a volcanic eruption, induced considerable degradation in land use conditions…this abrupt climatic change caused abandonment of Tell Leilan, regional desertion, and collapse of the Akkadian empire based in southern Mesopotamia.

Synchronous collapse in adjacent regions suggests the impact of abrupt climatic change was excessive."

(This is according to a statement made in 1993 by Harvey Weiss, professor of Near Eastern archaeology at Yale University).

The site of Tell Leilan was abandoned soon after the city's massive walls were constructed, its temple rebuilt and its grain production reorganized.

The debris, dust, and sand that followed show no trace of human activity.

Soil samples show fine wind-blown sand, no trace of earthworm activity, reduced rainfall and indications of a drier and windier climate.

Evidence shows that skeleton-thin sheep and cattle died of drought, and up to twenty-eight thousand people abandoned the site, seeking wetter areas elsewhere.

Shamshi-Adad I of Assyria, another Amorite, is he most powerful ruler in Mesopotamia immediately preceding the rise of Hammurabi of Babylon.

His father Ila-kabkabu ruled a kingdom on the borders of Mari and was an Amorite.

Upon his father's death, the kingdom was inherited by another brother, leaving Shamshi-Adad to build his own from scratch.

He first conquers Shekhna and renames the city Shubat-Enlil.

The modern name of the site is Tell Leilan.

He then seizes the fortress Ekallatum on the left bank of the Tigris.

This is accomplished only on the second try: a first attempt failed, after which Shamshi-Adad fled to Babylon.

He returned eventually and was successful.

This conquest makes it possible for him to control the city-state of Assur, which is a flourishing city that trades heavily with Anatolia.

He puts his first son, Ishme-Dagan I, on the throne of Ekallatum and continues his expansion.

Shamshi-Adad, with the annexation of Mari, rules a large empire, controlling the whole of Upper Mesopotamia.

On inscriptions Shamshi-Adad boasts of erecting triumphal stelae on the coast of the Mediterranean, but these probably represent short expeditions rather than any attempts at conquest.

Shamshi-Adad also proclaims himself as "king of all", the title used by Sargon of Akkad.

His rise to glory natutrally has earned him the envy of neighboring kings and tribes, and he and his sons face several threats to their control throughout his reign.

Ishme-Dagan probably is a competent ruler but his brother Yasmah-Adad appears to have been a man of weak character.

Shamshi-Adad is a great organizer and he keeps a firm controls on all matters of state, from high policy down to the appointing of officials and the dispatching of provisions.

His campaigns are meticulously planned, and his army knows all the classic methods of siege craft, such as encircling ramparts and battering rams.

Spies and propaganda are often used to win over rival cities.

Assyria loses its independence to a dynasty of Amorite descent from Terqa, a city near Mari, on the Euphrates River, when a member of this dynasty conquers Assyria and reigns from around 1740 BCE as Shamshi-Adad I, his kingdom extending from the Euphrates to the Zagros Mountains.

The capital of this Old Assyrian kingdom, called Shubat-Enlil, is founded some distance from Urkesh at another Hurrian settlement in the Khabur River valley, modern Tell Leilan.

Shamshi-Adad I dies around 1718 BCE; his son, Ishme-Dagan, is defeated by Hammurabi of Babylon, who thus establishes himself as ruler of Assyria.

The conquest of the Khabur River valley region by the Amorite king Shamshi-Adad I, who lived from about 1765 BC to 1700 BCE, had revived the abandoned site of Shekhna, present Tell Leilan.

Shamshi-Adad, seeing the great potential in the rich agricultural production of the region, had made it the capital city of his northern Mesopotamian kingdom and renamed it from Shekhna to Shubat-Enlil, meaning "the residence of the god Enlil" in the Akkadian language.

A royal palace has been built and a temple acropolis to which a straight paved street leads from the city gate.

There is also a planned residential area and the entire city is enclosed by a wall.

Shubat-Enlil, covering about ninety hectares, or more than two hundred and twenty-two acres, may have a population of twenty thousand people at its peak.

Shamshi-Adad’s eventual conquest of the fortress of Ekallatum on the left bank of the Tigris had made it possible for him to control the city-state of Assur, a flourishing city that trades heavily with Anatolia.

His rise to glory had earned him the envy of neighboring kings and tribes, and throughout his reign, he and his sons had faced several threats to their control.

While Ishme-Dagan, whom his father had placed on the throne of Ekallatum, probably was a competent ruler, his brother Yasmah-Adad, charged with the rule of Mari, appears to have been a man of weak character.

Shamshi-Adad had continued to strengthen his kingdom throughout his life, but upon his death it soon began to crumble.

The empire lacks cohesion and is in a vulnerable geographical position.

When the news of Shamshi-Adad's death spread, his old rivals at once set out to topple his sons from the throne.

Yasmah-Adad had been expelled from Mari in 1779 by Zimrilim, the son and heir of the previous ruler, and the rest of the empire would soon be lost to Hammurabi of Babylon.

Shamshi-Adad had continued to strengthen his kingdom throughout his life, but upon his death, it had soon begins to crumble.

The empire lacks cohesion and is in a vulnerable geographical position.

When the news of Shamshi-Adad's death spreads, his old rivals at once set out to topple his sons from the throne.

Yasmah-Adad is soon expelled from Mari by Zimri-Lim, and the rest of the empire is soon lost to Hammurabi of Babylon.