 The measurement refers to the traditional size of a Japanese flooring mat called a Tatami mat (made of woven dried grass) which were positioned to completely cover the floor of traditional Japanese homes, therefore it became a convenient measurement tool as the mats size was standardized hundreds of years ago.In Taiwan the measurement units are pronounced in Taiwanese Hokkien and Hakka before the World War II and adopted by the Mandarin speaking immigrants from China in 1949.Today, the Taiwanese units are used exclusively, in some cases alongside official metric (SI) units, and in other cases they have been supplanted by metric units.