Raiden was a Goa'uld who never achieved the rank of System Lord, despite owning a small empire in the Milky Way galaxy. He was said to have prevented the Mongols from invading Japan by sending down a shower of lightning arrows on their fleets—it is unknown if there was any truth to this, but it is possible that the "lightning arrows" were in fact staff weapon blasts. What is known is that Raiden defended the land of Nihon from Mongol raiders and, as punishment for attacking, he took the Mongols from Earth to the world of Simarka where they served him until their eventual rebellion.
Styling himself in the manner of a Japanese Emperor much like Yu, Raiden maintained a moderately-sized power base in a remote area of Goa'uld space bordering Yu's domain. It was because of this close proximity that the two Goa'uld often battled over the planets between their two domains and, despite Yu's greater numbers, the battles were evenly matched with each Goa'uld claiming victory on one world only to suffer defeat on the next.
Raiden's domain contained twelve planets, though only four of them had Stargates, and was patrolled by his seven ha'tak motherships alongside nearly two dozen al-kesh bombers. In order to keep control of his planets, Raiden structured his empire in a manner similar to feudal Japan, appointing a Shogun for every planet who also had daimyo's serving under them to control each region on the planet. These worlds were all populated by people of Asian descent, primarily Japanese but with a mix of Chinese on a number of worlds—particularly those that Raiden had captured from Yu. The culture and society of these people was similar to that of 14th century Japan, apparently kept at that level by Raiden.
The best-defended world in Raiden's empire was Kyoto, home to most of his Jaffa as well as serving as the training ground for all of his warriors. It was here that Raiden housed several Goa'uld laboratories which researched new technology to boost Raiden's technological advantage over his foes wherever possible. Among the advances designed by these laboratories were Raiden's Thunder and Lightning staves which were adapted from the standard staff weapon. Raiden's other worlds included Akita, Mito, Naha, Tosa and, formerly, Simarka.
Despite having a well-defended world, Raiden chose one of his ha'tak's, the Katana, as his base of operations as well as his flagship. It is perhaps because of this mobile base of operations that he has survived so long against such superior foes, as it made him a very difficult target to take out. Indeed, he went so far as removing the Stargate from Kyoto and placing it on board the Katana so that he would be able to use a Stargate whenever orbiting a planet.
Raiden had two very distinct sects of Jaffa serving him directly, the Thunder and Lightning Guards, each of which used their respective weapons from Raiden's research, who were trained in a remote monastery near Kyoto's capital city. As with the Jaffa of other Goa'uld, these troops were unquestionably loyal to Raiden and would sooner die than betray their master. In addition to these troops using weapons which could mimic the legendary abilities of their god, Raiden also equipped his personal kara kesh with a technological system which could mimic thunder and lightning when it was used to attack his enemies. (RPG: "Fantastic Frontiers: Stargate Season One")