The Mongol wars in China ran for nearly seventy years, from the first attacks on the Jin in 1211 to the destruction of the Southern Song in 1279. The demographic evidence is a registration record with an enormous gap: the Jin census of 1207 recorded roughly 7.6 million households and about 45 million people in north China, while the Mongol registration of north China in the 1230s recorded under two million households. That collapse has often been read directly as tens of millions of deaths. Specialists are more cautious. Yuan registration was far less thorough than Jin registration, much of the population escaped enrolment or was assigned to Mongol nobles as bondservants and so left the ordinary registers, and there was heavy flight to the south. The Cambridge Economic History of China and the demographic work of Ho Ping-ti treat much of the apparent loss as administrative. Real mortality in the north from warfare, famine and epidemic was nonetheless severe, and the conquest of the Song, achieved partly by negotiated surrenders, was less destructive than the northern wars.
Mongol armies under Chinggis Khan, Ögedei and Khubilai destroyed the Jin empire in northern China and then the Southern Song, killing, deporting artisans and reordering the population under the Yuan dynasty
Chinese household registers are the best pre-modern demographic series anywhere: the Jin census of 1207 recorded about 8.4 million households and 53.5 million people, and Southern Song registers imply a comparable or larger population, for a combined total usually given as 100-120 million around 1200. The Yuan census of 1290 counted about 58.8 million. Historians divide over how much of that fall represents deaths and how much represents the collapse of registration, tax flight and the loss of southern records.
The upper figure is the commonly quoted death toll derived from subtracting Mongol-era registration totals from Jin-era ones. Specialists including Ho Ping-ti and the contributors to the Cambridge Economic History of China attribute a large part of that gap to changes in registration coverage, flight and the removal of populations into noble households. Real excess mortality in north China was heavy but has never been separately reconstructed, so no defensible lower bound exists.
The killing of urban populations at Zhongdu and elsewhere, the deportation and assignment of artisans and captives, and the devastation of the north China countryside are documented in the Jin and Yuan dynastic histories.
China, Mongolia