Complex sentence: The alien race known as the Yuuzhan Vong are preparing for their invasion on the "Star Wars" galaxy by covertly disrupting the peace established by that of the New Republic ever since the fall of the Galactic Empire years previously.
Split into simpler sentences: The alien race known as the Yuuzhan Vong are preparing for their invasion on the "Star Wars" galaxy. They are doing this by covertly disrupting the peace established by that of the New Republic ever since the fall of the Galactic Empire years previously.