The Akkadian Dynasty had had a line of ten successful Pharoahs, all of whom were fairly competent and able. But the eleventh, twelth, and thirteenth Pharoahs each progressly displayed signs of decadence, apathy, ineptitude, and plain stupidity. Power continuously passed into the hands of the priests and local warlords. Of course, the Pharoahs were all too busy living their lavish lifestyle to notice or care.
During the reign of the fourteenth Pharoah, very significant events occurred. First off, a massive famine occured (always a famine, eh?) and the people starved. The Pharoah said "pooey" and ignored their pleas for government intervention. This really angrified the commoners, but the priests got rich off from it by selling their personal stocks of grain.
Then, a long lost relative of the Pharoah's declared himself rightful ruler of Akkadia and set himself up in the south. No one important really listened to him because he was a bastard child and because he smelled like fish. So, an army was dispatched to defeat the pretender, an army lead by a famous and well beloved general. Unfortunately for the general, the army was poorly equipped because the Pharoah had spent a large chunk of the money to build himself a new floating palace. So, the army was defeated, the famous general returned in disgrace. The Pharoah was very angry and had him and his entire family executed. This pissed off the military greatly. But of course, the Pharoah was oblivious. Eventually, another army was sent and the pretender was defeated and executed.
And then, the priests were angry. Angry primarily because the Pharoah had been slipping in his religious duties and began displaying a malice and contempt for the gods. Oh, the priests couldn't have this.
The final blow, or biggest threat, came from the Pharoah's own nephew. The nephew was quite a charismatic character, and also a self proclaimed messiah. He claimed to be the reincarnate of the sun god Amun Ra. He claimed he was born again to reclaim Akkadia and purge it of the vileness and sin that had taken root. No one would have taken him seriously, but he did a few magic tricks and was thus proclaimed the messiah. The nephew wasn't very happy with the way the Pharoah was running things, so he conspired with the priests and generals to overthrow the Pharoah. And they overthrowed quite extravagantly, by publically sacrificing the Pharoah.
Now the question surfaced: who would rule? The messiah nephew had no chance of being absolute monarch as his ancestors did, the priests and military had become too strong. Another factor also emerged, the first organizations of unions. Tired of being trampled on, the workers of Akkadia banded together and formed unions, although they were more like local militias and gangs. The messiah nephew wanted to avert a civil war, so he created a radically new system of government.
The government would consist of a council, with two councilmembers from the military, religious, and worker classes. The messiah nephew would head of the council. The council acted as the executive and legislative branch, with each councilmember having an equal voice. The class divisions of the council would soon be solidified into caste divions. Exactly 1/3 of the population was the worker caste (artisans, laborers, merchants), 1/3 religious (priests, scholars, philosophers, ambassadors, doctors, judges), and the last 1/3 military (soldiers, police, firemen, weaponmakers). The caste system would eventually stamp out all intra-Akkadian hostilities and pretty much ensured each caste had equal voice in the government.
As for the messiah, he instituted a new form of Egyptian mythology, called Copticism. He claimed the Amun Ra was the one and only god, all other gods are incarnations the Ra uses to govern the universe. He claimed of a life after death where all those who worshipped Ra were granted eternal bliss, and all those who defied Ra were sent to the deepest pits of space. And being the reincarnation of Amun Ra, the messiah was naturally worshipped like a god (much like the Pharoahs before him). In his fifth year of reigning, the messiah suddenly died. The priests said that he got up one day and went back to the heavens. The true reason is that the messiah had grown quite lazy and partied too much, the priests wanted to martyr him before he ruined their religion.