monument dating to 823 and setting out the terms of peace and borders between Tibet and China arrived at in 821 can still be seen in front of the Jokhang temple in Barkhor Square in Lhasa. The monument, a treaty of friendship, is written in both Tibetan and Chinese. The inscribed pillar was erected by the Chinese in 1793 during a smallpox epidemic. It records the Sino-Tibetan treaty of 822 concluded by King Ralpacan and includes the following inscription: "Tibet and China shall abide by the frontiers of which they are now in occupation. All to the east is the country of Great China; and all to the west is, without question, the country of Great Tibet. Henceforth on neither side shall there be waging of war nor seizing of territory. If any person incurs suspicion he shall be arrested; his business shall be inquired into and he shall be escorted back." The inscription also carried advice on hygiene measures to prevent smallpox. The relations between the two countries appears to have been complex. On the one hand, the monument describes connections between China and Tibet as similar to those between uncle and nephew. The Tang dynasty of China and the Yarlung dynasty of Tibet were indeed related by marriage, yet the terms uncle and nephew are not used in relation to other groups with whom the Chinese had connections by marriage. On the other hand, the monument seems to describe the two countries as equals. The text has been published several times. Mongol conquest and Tibet under the Yuan dynasty After the Mongol Prince Köden took control of the Kokonor region in 1239, in order to investigate the possibility of attacking Song China from the West, he sent his general Doorda Darqan on a reconnaissance mission into Tibet in 1240. During this expedition the Kadampa (Bka'-gdams) monasteries of Rwa-sgreng and Rgyal-lha-khang were burned, and 500 people killed. The death of Ögödei the Mongol Khan in 1241 brought Mongol military activity around the world ground, temporarily, to a halt. Mongol interests in Tibet resumed in 1244 when Prince Köden sent an invitation to Sakya Pandita (1182–1251) to come to his capital and formally surrender Tibet to the Mongols. Sakya Pandita arrived in Kokonor with his two nephews 'Phags-pa (1235–80) and Phyag-na Rdo-rje (1239–67) in 1246. After an internecine feud among the Mongol princes Kublai was appointed by Möngke Khan to