King Sejong's reign in the Joseon period witnessed a great advancement in medical systems. Significant academic achievements in medicine were made as can be seen in the publications of such medical texts as Hyangyak jipseong bang 鄕藥集成方 and Euibang ryuchui 醫方類聚. Formal medical systems were also established during this time. In addition, King Sejong’s government promulgated policies to secure medicinal materials that were essential for treating illnesses. To maximize the use of domestic medicine, or hyangyak, the government commissioned the publications of Hyangyak chaechui wolryeong 鄕藥採取月令 and Hyangyak jipseong bang, carried out systematic comparisons between the efficacy of domestic medicine and that of Chinese medicine, and devised various measures for stabilizing the supply of medicinal materials from different regions of the country. As it was proven difficult to immediately increase the supply and use of medicinal materials, however, efforts were also made to develop alternative treatments. One notable example was the use of steam bath, or hanjeung 汗蒸. Steam bath refers to the treatment by sweating, and appeared first in Qianjin fang 千金方, a medical text published in China during the Tang Dynasty. King Sejong supported the steam bath treatment and allowed the establishment and operation of steam bath places, or hanjeungso 汗蒸所, as a way to treat contagious diseases. Later, as more advanced medical theories were introduced and the risks of steam bath treatment became known, and as it became easier to get medicinal materials, the government gradually lost interest in the steam bath treatment. However, due to its affordable price, the steam bath treatment remained popular as a folk remedy, particularly in the northern parts of the kingdom until late in the Joseon Dynasty.