section_path: 14th-century plague/Transmission/Territorial origins
section_name: Territorial origins
paragraph_text: Territorial origins
  
  According to a team of medical geneticists led by Mark Achtman, Yersinia pestis "evolved in or near China" over 2,600 years ago. Later research by a team led by Galina Eroshenko placed its origins more specifically in the Tian Shan mountains on the border between Kyrgyzstan and China. However more recent research notes that the previous sampling contained East Asian bias and that sampling since then has discovered strains of Y. pestis in the Caucasus region previously thought to be restricted to China. There is also no physical or specific textual evidence of the Black Death in 14th century China. As a result, China's place in the sequence of the plague's spread is still debated to this day. According to Charles Creighton, records of epidemics in 14th-century China suggest nothing more than typhus and major Chinese outbreaks of epidemic disease post-date the European epidemic by several years. The earliest Chinese descriptions of the bubonic plague do not appear until the 1640s.
  
  Nestorian gravesites dating from 1338 to 1339 near Issyk-Kul have inscriptions referring to plague, which has led some historians and epidemiologists to think they mark the outbreak of the epidemic; this is supported by recent direct findings of Y. pestis DNA in teeth samples from graves in the area with inscriptions referring to "pestilence" as the cause of death. Epidemics killed an estimated 25 million across Asia during the fifteen years before the Black Death reached Constantinople in 1347.
  
  The evidence does not suggest, at least at present, that these mortality crises were caused by plague. Although some scholars, including McNeill and Cao, see the 1333 outbreak as a prelude to the outbreaks in Europe from the late 1340s to the early 1350s, scholars of the Yuan and Ming periods remain skeptical about such an interpretation. Nonetheless, the remarkably high mortality rates during the Datong mortality should discourage us from rejecting the possibility of localized/regional outbreaks of plague in different parts of China, albeit differing in scale from, and unrelated to, the pandemic mortality of the Black Death. What we lack is any indication of a plague pandemic that engulfed vast territories of the Yuan Empire and later moved into western Eurasia through Central Asia.
  
  According to John Norris, evidence from Issyk-Kul indicates a small sporadic outbreak characteristic of transmission from rodents to humans with no wide-scale impact. According to Achtman, the dating of the plague suggests that it was not carried along the Silk Road, and its widespread appearance in that region probably postdates the European outbreak. Additionally, the Silk Road had already been heavily disrupted before the spread of the Black Death; Western and Middle Eastern traders found it difficult to trade on the Silk Road by 1325 and impossible by 1340, making its role in the spread of plague less likely. There are no records of the symptoms of the Black Death from Mongol sources or writings from travelers east of the Black Sea prior to the Crimean outbreak in 1346.
  
  Others still favor an origin in China. The theory of Chinese origin implicates the Silk Road, the disease possibly spreading alongside Mongol armies and traders, or possibly arriving via ship—however, this theory is still contested. It is speculated that rats aboard Zheng He 's ships in the 15th century may have carried the plague to Southeast Asia, India, and Africa.
  
  Research on the Delhi Sultanate and the Yuan dynasty shows no evidence of any serious epidemic in fourteenth-century India and no specific evidence of plague in 14th-century China, suggesting that the Black Death may not have reached these regions. Ole Benedictow argues that since the first clear reports of the Black Death come from Kaffa, the Black Death most likely originated in the nearby plague focus on the northwestern shore of the Caspian Sea.
  
  Demographic historians estimate that China's population fell by at least 15 per cent, and perhaps as much as a third, between 1340 and 1370. This population loss coincided with the Black Death that ravaged Europe and much of the Islamic world in 1347–52. However, there is a conspicuous lack of evidence for pandemic disease on the scale of the Black Death in China at this time. War and famine – and the diseases that typically accompanied them – probably were the main causes of mortality in the final decades of Mongol rule.
  
  Monica Green suggests that other parts of Eurasia outside the west do not contain the same evidence of the Black Death, because there were actually four strains of Yersinia pestis that became predominant in different parts of the world. Mongol records of illness such as food poisoning may have been referring to the Black Death. Another theory is that the plague originated near Europe and cycled through the Mediterranean, Northern Europe and Russia before making its way to China. Other historians, such as John Norris and Ole Benedictaw, believe the plague likely originated in Europe or the Middle East, and never reached China. Norris specifically argues for an origin in Kurdistan rather than Central Asia.