In the sixth decade of the thirteenth century, the armies of the Mongol Empire were on the march in Poland, Galicia, Syria, Iraq, Iran, Kashmir, southern China, Tibet, the Indochinese peninsula, and Korea. These operations were launched by Grand Qan Mongke (r. 1251-59) in an attempt to implement the mandate of Chinggis Qan and "that the Tatars should conquer every country in the world. and " These campaigns were undertaken on a gigantic scale, in sonic cases involving hundreds of thousands of men and enormous quantities of supplies. Behind each campaign lay months or years of careful preparation. Tactical, topographical, and logistical problems were first subjected to careful investigation, and then specific and detailed orders were issued to the responsible military commanders.