With the assistance of Batu, Möngke succeeded as Great Khan in 1251. Utilizing the discovery of a plot designed to remove him, Möngke as the new Great Khan began a purge of his opponents. Estimates of the deaths of aristocrats, officials, and Mongol commanders range from 77 to 300. Batu became the most influential person in the Mongol Empire as his friendship with Möngke ensured the unity of the realm. Batu, Möngke, and other princely lines shared rule over the area from Afghanistan to Turkey. Batu allowed Möngke's census takers to operate freely in his realm. In 1252–1259, Möngke conducted a census of the Mongol Empire, including Iran, Afghanistan, Georgia, Armenia, Rus', Central Asia, and North China. While the census in China was completed in 1252, Novgorod in the far northwest was not counted until winter 1258–59.