Original sentence: According to the fringe author Zecharia Sitchin, the Sumerians called a celestial body that once existed where an asteroid belt now exists as Tiamat, but scholars of archeology and astronomy strongly dispute the idea that a planet existed there in human history or that the Sumerians actually believed this
Edited sentence: Tiamat was the name of the celestial body that once existed where the asteroid belt now exists according to the Sumerians, as researched by Zecharia Sitchin