Some scholars estimate that about 80% of the 600,000 or more Dzungar were destroyed by a combination of disease and warfare. Outer Mongolia was given relative autonomy, being administered by the hereditary Genghisid khanates of Tusheet Khan, Setsen Khan, Zasagt Khan and Sain Noyon Khan. The Jebtsundamba Khutuktu of Mongolia had immense ''de facto'' authority. The Manchu forbade mass Chinese immigration into the area, which allowed the Mongols to keep their culture. The Oirats who migrated to the Volga steppes in Russia became known as Kalmyks.