The Guardian at www.guardian.co.uk/news/2012/sep/23/weatherwatch-climate-ghengis-khan-mo… … eager to publish anthing about warm weather the Guardian informs us that tree rings in the early 13th century Mongolia were very wide and this implies the temperature was warm. As a result of this there would have been a lot of grass growing on the Mongolian steppe, more than enough to feed the thousands of horses the great armies of the Mongols relied on. As Genghis Khan emerged as a result of cool weather that reduced pasture, mainly because cold springs and autumns led to a reduced growing season, we have to assume the climate cheered up and pasture became abundant about the time he was in the final stages of suppressing local opposition. However, tree rings then became very narrow – in 1258. It is suggested by the journalist writing the piece that a sudden lurch back into cold weather was what caused Kublai Khan to move his Mongol court into China, setting up in Beijing. I thought I would take a look at this and found that 1258 was the year in which Kublai Khan invaded China (Chronology of World History, Mellish, Storey, Williams and Waller) and it was also the year in which Korean resistance came to an end and they accepted Mongol rule. Presumably this means the Mongols swept across the top of China. However, it was also the year in which other Mongol armies perpetrated disaster, sacking Baghdad for example. In 1260 Hulugu the Mongol general seized control of all Syria and in 1261 Kublia Khan had Beijing rebuilt as his winter capital. In other words he had conquered northern China by 1261 but was still in the process of defeating southern China – in the 1270s, taking the Sung capital as late as 1276. Mongol fortunes everywhere began to wane in the 14th century – and that probably had something to do with climate, followed by the plague. So, is the Guardian journalist telling us porkies or has he not looked no further than the earlier claim that 1258 was the year in which a volcano blew somewhere in the world and caused a famine in London, explaining away the mass graves at Spitalfields, or was 1258 a short lived blip that may have led to the surrender of the Koreans but little else?