was assassinated in July 1287. The Mongols once again invaded south toward Pagan. Recent research indicates that Mongol armies may not have reached Pagan itself, and that even if they did, the damage they inflicted was probably minimal. But the damage was already done. All the vassal states of Pagan revolted right after the king's death, and went their own way. In the south, Wareru, the man who had seized the governorship of Martaban in 1285, consolidated Mon-speaking regions of Lower Burma, and declared Ramannadesa (Land of the Mon) independent in 1287. In the west too, Arakan stopped paying tribute. The 250-year-old Pagan Empire had ceased to exist. Warring states period The political vacuum created by the sudden collapse of Pagan triggered constant warfare that would engulf the Irrawaddy valley and its periphery for the next 350 years. In retrospect, the two centuries of peace and order maintained by the Pagan Empire turned out to be rather remarkable. The main cause for warfare was that no strong polity emerged to reunite the kingdom. After their 1287 invasion, the Mongols moved farther south to Tagaung but refused to fill in the power vacuum they had created. Indeed, Emperor Kublai Khan never sanctioned an actual occupation of Pagan. His real aim appeared to have been "to keep the entire region of Southeast Asia broken and fragmented." Last Mongol invasion At Pagan, the new king Kyawswa controlled just a small area outside the capital. Instead, the real power rested with three former Pagan commanders of nearby Myinsaing. It was the brothers, not the nominal sovereign Kyawswa, that sent a force to retake Lower Burma in 1294 after Wareru had decided to become a vassal of the Sukhothai Kingdom. Wareru drove back the Myinsaing forces. Concerned by the increasing power of the three brothers, Kyawswa submitted to the Mongols in January 1297, and was recognised by the Mongol emperor Temür Khan as viceroy of Pagan on 20 March 1297. In December 1297, the three brothers overthrew Kyawswa, and founded the Myinsaing Kingdom. In January 1300, the Myinsaing forces led by Athinhkaya seized the southernmost Mongol garrisons named Nga Singu and Male, just north of modern Mandalay. On 22 June 1300, the Mongol Emperor declared that Kumara Kassapa, one of Kyawswa's sons, was the rightful king of Burma, and sent in a 12,000-strong army from Yunnan. The Mongol army reached Male on 15 January 1301,