Garenjazz had dreamed a dream.
This was a dream he had created for a long time. He started off with very few things. He had to develop the science to bring actual physical items into his dream world.
Years and decades passed and his Throne was slowly assimilated inside. This was why he didn't appear to have a Throne on his apeparances outside as he had always had his throne 'in his dreams.' Soon his entire ship assimilated into the dream.
In time, the dream world grew and had numerous items inside. He had a spatial realm, he had beings that were a product of his imagination within that world of his own. He had weapons and ships, and other things.
Soon, his items, his servants, and the technology within the dream world had already surpassed the physical as his imagination could create these very items and objects.