Hua Mulan is a heroine from a Chinese legend, so it is unknown if, when and how she died. All that is known about Hua Mulan was written in the "Ballad of Mulan," an ancient Chinese poem. Disney made a film based off of this ballad called, "Mulan," which popularized the legend in the United States.
"The Ballad of Mulan" begins with Mulan learning that the Emperor is recruiting for a war against nomadic tribes and Mongols. Each family is required to produce a male to join the Emperor's troops. Mulan's father is to old to go to war and survive it, and there are no other males in her family, so Mulan poses as his son and takes his place. She fights for 12 years, during which time she received many promotions due to her skill and bravery during battles. At the end of the ballad, the troops return home where many, including Mulan, are offered permanent posts in the military. Hua Mulan declines, and instead decides to return to her family to live a peaceful life. When she dresses women's clothing, her fellow soldiers are amazed to realize that the brave and skilled Mulan was a woman after all.