Osirion’s history is longer than that of any other nation currently on Golarion. It’s past can be broken into three periods, each with it’s own “age,” during which Osirion existed in some form or another.
Founded by the first pharaoh, Azghaad, only centuries after Earthfall wiped civilization from the face of Golarion, it’s rulers dedicated themselves to their patron deity, Nethys, calling themselves god-kings to honor his patronage of them. As their empire expanded, these pharaohs soon came into conflict with the only other society developing at the time, the Jistka Imperium. The two powers warred from opposite sides of Garund, forcing the scattered bands and tribes between the them to eventually unify into the Tekritanin League. In the end, Osirion resorted to necromancy and daemonology to crush their rival and absorb the tentatively allied League as one of it’s territories.
This is Osirion’s First Age, a time characterized by tumult and chaos as much as by the nation’s rapid growth. It’s peak was when the Pharaoh of Dark Plagues tempted Ahriman into the world. The demigod’s support allowed Osirion to swiftly defeat the technologically and magically superior nation to the west and turn their attentions south to Lirgen and Yamasa. Yamasa, inspired by Lirgen’s utter fall, turned their renowned prophetic abilities toward strategic needs, barely managing to hold back the tide of imperialism. On the other side of Garund, Nex is forced to advance rapidly to keep Osirion from expanding beyond modern day Katapesh. Only an eventual betrayal by Ahriman ultimately stymied the empire’s great hopes. The Pharaoh of Dark Plagues was eventually removed from power by a massive uprising, having ignored his subjects in his mad quest of ambition.
Osirion’s Second Age begins in a time of civil war, when the country was split into four factions, each sporting it’s own god-king. Eventually peace was struck and the rivals ruled Osirion as a council. Known as the Four Pharaohs of Ascension, this alliance ushered in what is now considered the true pinnacle of Osirion power and prosperity. Unfortunately, this wealth brought with it an arrogance and extravagance which corrupted those rulers that followed the Pharaohs of Ascension. In the end, Osirion’s self-obsession caused a level of negligence that resulted in the nation’s conquest by the Keleshite Empire to the east. For the next 3,000 years Osirion would be ruled by that distant and aggressive nation.
The Third Age of Osirion begins with Khemet I, whose line stretches all the way back to Azghaad I, reclaiming the throne. Today his grandson, the Ruby Prince, rules, having inherited the title of Pharaoh from his father. The country’s long and troubled history has left ruins and treasures scattered across the sands of all of northern Garund. It remains to be seen what glory this Third Age may bring.