In August 1227, during the fall of Yinchuan, the capital of Western Xia, Genghis Khan died. The exact cause of his death remains a mystery, and is variously attributed to being killed in action against the Western Xia, illness, falling from his horse, or wounds sustained in hunting or battle. According to The Secret History of the Mongols Genghis Khan fell from his horse while hunting and died because of the injury. He was already old and tired from his journeys. The Galician–Volhynian Chronicle alleges he was killed by the Western Xia in battle, while Marco Polo wrote that he died after the infection of an arrow wound he received during his final campaign. Later Mongol chronicles connect Genghis' death with a Western Xia princess taken as war booty. One chronicle from the early 17th century even relates the legend that the princess hid a small dagger and stabbed him, though some Mongol authors have doubted this version and suspected it to be an invention by the rival Oirads.