under
Batu Khan (with sword). Ancient sources described Genghis Khan's conquests as wholesale destruction on an unprecedented scale in certain geographical regions, causing great
demographic changes in Asia.
Ibn Al-Athir wrote that Mongol invaders massacred and killed about 700,000 people in
Merv. Mustawfi, likewise, wrote that
Merv was still in ruins in the middle of the 14th century.
Hamdallah Mustawfi, who completed Tarikh-i Guzida in 1330, states that 800,000 people were killed and massacred during
Hulagu's siege of Baghdad in 1258. While Smith concedes much of what Middle Eastern "chroniclers produced [were] exaggarated estimates", he then goes on to ennumarate the total population of
Persia as reduced from 2,500,000 to 250,000 as a result of mass extermination and famine. Population exchanges also sometimes occurred. but most of the
Tanguts including children and women were massacred and killed by the army of Mongol invaders under
Genghis Khan. According to
John Man the
Tangut Empire is little known to anyone other than experts in the field due to Genghis Khan's policy calling for their complete destruction. He states that "There is a case to be made that this was the first ever recorded example of attempted
genocide. It was certainly very successful
ethnocide." The book has since been criticized for lacking a solid basis for many of its population estimates. In addition, the source used by McEvedy and Jones to support their claim of 35 million deaths in China during the Mongol conquests, "The population statistics of China, A.D. 2–1953" by John Durand, casts doubt on their conclusions. Durand points out that the Mongol censuses were likely very incomplete, leading to an exaggeration of the population decrease. According to Diana Lary, the Mongol invasions induced population displacement "on a scale never seen before" in Eurasia, but especially in China, where the massive southward migration of Northern Chinese refugees actually managed to merge the southern and northern parts of China, an unexpected historical consequence. China suffered a drastic decline in population in the 13th and 14th centuries. Before the
Mongol invasion, Chinese dynasties reportedly had approximately 120 million subjects; after the conquest had been completed in 1279, the 1300 census reported roughly 60 million people. While it is tempting to attribute the major decline solely to Mongol ferocity, scholars now have mixed sentiments on the subject. The South Chinese might account for 40 million unregistered persons who, without passports, would not have appeared in the census. Entire peasant populations joining or enlisted for labor could result in a large population reduction because of food shortages. Scholars such as Frederick W. Mote argue that the wide drop in numbers reflects an administrative failure of records, rather than a
de facto decrease, but others, such as Timothy Brook, argue that the Mongols created a system of enserfment of a huge portion of the Chinese populace, causing many to disappear from the census altogether. Other historians, like William McNeill and David Morgan, argue that the
Black Death, partially spread by the Mongols, was the main factor behind the demographic decline in that period. The plague also spread into areas of Western Europe and Africa that the Mongols never reached. The Mongols practiced biological warfare by catapulting diseased cadavers into the cities they besieged. It is believed that fleas remaining on the bodies of the cadavers may have acted as vectors to spread the Black Death. Colin McEvedy estimates the population of
European Russia dropped from 7.5 million prior to the invasion to 7 million after it. == Destruction of culture and property ==