Chinese legends of geese include the story of Su Wu: in the days of old, old Su Wu, spent 19 years, captive of Xiongnu. There is a story about Su Wu which became a common allusion in Chinese poetry. Su Wu was an historical figure, however his legend has evolved into the folk realm. There are thus many variations of his story, though much can be attested to historically. The rival Chinese and Xiongnu empires battled in the Han–Xiongnu War from 133 BCE to 89 CE. In 100 BCE, The Chinese emperor, Han Wudi (the "martial emperor of Han") sent his official Su Wu on a mission to Xiongnu (Murck, 75). Su lead a diplomatic mission of several official envoys to the Xiongnu ruler, Chedihou, whose official title was Chanyu. The Chinese delegation became embroiled in a plot against the Xiongnu leadership; and, upon the plot's failure, they were all arrested. Some of the Chinese delegates were killed, and Su Wu was put into captivity, where he remained for 19 years.