In the confusion which ensued, Tushratta was murdered by Sutarna II, who was recognized by Subbi-luliuma.  The crown prince, Mattiuza, fled to Babylon, where he found protection, but was unable to receive any assistance.  Ultimately, when the Hittite emperor had secured his sway over northern Syria, he deposed Sutarna II and set Mattiuza as his vassal on the throne of the shrunken Mitanni kingdom.

Meanwhile the Egyptian empire in Asia had gone to pieces.  When Akhenaton, the dreamer king, died in his palace at Tell-el-Amarna, the Khabiri were conquering the Canaanite cities which had paid him tribute, and the Hittite ruler was the acknowledged overlord of the Amorites.

The star of Assyria was also in the ascendant.  Its king, Ashur-uballit, who had corresponded with Akhenaton, was, like the Hittite king, Subbi-luliuma, a distinguished statesman and general, and similarly laid the foundations of a great empire.  Before or after Subbi-luliuma invaded Tushratta’s domains, he drove the Mitannians out of Nineveh, and afterwards overcame the Shubari tribes of Mitanni on the north-west, with the result that he added a wide extent of territory to his growing empire.

He had previously thrust southward the Assyro-Babylonian frontier.  In fact, he had become so formidable an opponent of Babylonia that his daughter had been accepted as the wife of Karakhardash, the Kassite king of that country.  In time his grandson, Kadashman-Kharbe, ascended the Babylonian throne.  This young monarch co-operated with his grandfather in suppressing the Suti, who infested the trade routes towards the west, and plundered the caravans of merchants and the messengers of great monarchs with persistent impunity.

A reference to these bandits appears in one of the Tell-el-Amarna letters.  Writing to Akhenaton, Ashur-uballit said:  “The lands (of Assyria and Egypt) are remote, therefore let our messengers come and go.  That your messengers were late in reaching you, (the reason is that) if the Suti had waylaid them, they would have been dead men.  For if I had sent them, the Suti would have sent bands to waylay them; therefore I have retained them.  My messengers (however), may they not (for this reason) be delayed."[301]

Ashur-uballit’s grandson extended his Babylonian frontier into Amurru, where he dug wells and erected forts to protect traders.  The Kassite aristocracy, however, appear to have entertained towards him a strong dislike, perhaps because he was so closely associated with their hereditary enemies the Assyrians.  He had not reigned for long when the embers of rebellion burst into flame and he was murdered in his palace.  The Kassites then selected as their king a man of humble origin, named Nazibugash, who was afterwards referred to as “the son of nobody”.  Ashur-uballit deemed the occasion a fitting one to interfere in the affairs of Babylonia.  He suddenly appeared at the capital with a strong army, overawed the Kassites, and seized and slew Nazibugash.  Then he set on the throne his great grandson the infant Kurigalzu II, who lived to reign for fifty-five years.