The Sith expansionary campaign was the name given to a series of aggressive actions made by the Sith Order of Decreto during the early 230’s ABY.
The Dark Lord of the Decreton Empire at the time; Darth Wyyrlok, having been criticized by many of the Sith Knights that he ruled, had decided that in order to keep the Decreton Empire in power over the galaxy, they needed to expand beyond its borders.
And so began a series of campaigns against many of the galaxies smaller, orbital, domains. And by the early 240’s ABY, the Sith had reached the nearest of the major galaxies. The former Yuuzhan Vong galaxy.
There they found something they were not expecting at all. A race of technologically-advanced Humans who were undaunted by the colossal Sith warships that faced them.
Fearful, the Sith attacked the alien race who had identified themselves as the Zao tenj. After their initial success the Sith soon found themselves been beaten back by the Zao tenj warships until only one vessel remained.
Fleeing into the abyss of space, the Sith warship made its way back to the home galaxy and informed the Dark Lord of the new threat. Wyyrlok, sensing the oncoming storm dissolved the Sith expansionary fleet into the main bulwark of the fleet and began preparations for war.