springs were recorded in the Tang dynasty. While royal bathhouses and bathrooms were common among ancient Chinese nobles and commoners, the public bathhouse was a relatively late development. In the Song dynasty (960–1279), public bathhouses became popular and ubiquitous, and bathing became an essential part of social life and recreation. Bathhouses often provided massage, manicure, rubdowns, ear cleaning, food and beverages. Marco Polo, who traveled to China during the Yuan dynasty, noted Chinese bathhouses used coal for heating, which he had never seen in Europe. At that time coal was so plentiful that Chinese people of every social class took frequent baths, either in public baths or in bathrooms in their own homes. A typical Ming dynasty bathhouse had slabbed floors and brick dome ceilings. A huge boiler was installed in the back of the house, connected with the bathing pool through a tunnel. Water could be pumped into the pool by turning wheels attended by staff. Indonesia Traditionally in Indonesia, bathing is almost always "public", in the sense that people converge at riverbanks, pools, or water springs for bathing or laundering. However, some sections of riverbanks are segregated by gender. Nude bathing is quite uncommon; many people still use kain jarik (usually batik clothes or sarong) wrapped around their bodies to cover their genitals. More modest bathing springs might use woven bamboo partitions for privacy, still a common practice in villages and rural areas. The 8th-century complex of Ratu Boko contains a petirtaan or bathing-pool structure enclosed in a walled compound. This suggests that other than bathing in riverbanks or springs, people of ancient Java's Mataram Kingdom developed a bathing pool, although it was not actually "public" since it was believed to be reserved for royalty or people residing in the compound. The 14th-century Majapahit city of Trowulan had several bathing structures, including the Candi Tikus bathing pool, believed to be a royal bathing pool; and the Segaran reservoir, a large public pool. The Hindu-majority island of Bali contains several public bathing pools—some, such as Goa Gajah, dating from the 9th century. A notable public bathing pool is Tirta Empul, which is primarily used for the Balinese Hinduism cleansing ritual rather than for sanitation or recreation. Its bubbling water is the main source of the Pakerisan River. Indus Valley Civilization Some of the earliest public baths are found in the ruins in of the Indus Valley civilization. According to