rde's suggestion would be good, but I think it is going to be from the ancients perspective, or maybe just from our perspective but without all our modern technology...
The Goa’uld Poseidon comes to Earth, after hearing about the rich pickings here, from other Goa'ulds in the System Lord Council. Egypt is pretty much full of Goa'ulds and so he builds an Empire centred on an island that he calls Atlantis. This island is in the Atlantic Ocean, located beyond the “Pillars of Herculesâ€, giant rocks which we now know of as the Straight of Gibraltar, but which were actually put there at the command of his First Prime Hercules, to defend Atlantis.
He fathers 10 Goa’uld ‘sons’, to help him build his Empire, the first of which, Atlas, has the continent and surrounding ocean named for him.
He builds a magnificent city surrounding his Mothership, which the Earth people know only as a Temple. Inside his ship he has a gold sarcophagus in his image, showing him driving six winged horses.
His power, and his Jaffa armies spread as far as Egypt and Italy, but could not conquer Greece because Hercules changed sides and helped the Greeks to defeat them. Hercules had discovered how to make a Naquada bomb by overloading the Mothership engines. In one day of violent Earthquakes and floods, the island sank into the sea, destroying all the Goa’ulds and Jaffa armies.
Hercules then leads an uprising against the other Goa'ulds on Earth. Shocked at the destruction of Atlantis and Poseidon, they all leave Earth never to return.
And whom have you got lined up to play Mother Bug? 
