Wat Phra That Doi Tung is popularly thought to be the site of the first chedi constructed in the Lanna Kingdom. According to legend, King Achutarat of Chiang Saen established it in the year 911 to enshrine a collar-bone relic of the Buddha brought from India. He demarcated the site by having numerous long flags (known as tung) raised atop the mountain (doi), which is why the site is known as Doi Tung (Flag Peak).