漢字文化圏
The sexagenary cycle, also known as the Stems-and-Branches or ganzhi, is a cycle of sixty terms, each corresponding to one year, thus a total of sixty years for one cycle, historically used for reckoning time in China and the rest of the East Asian cultural sphere. It appears as a means of recording days in the first Chinese written texts, the Shang oracle bones of the late second millennium BC. Its use to record years began around the middle of the 3rd century BC. The cycle and its variations have been an important part of the traditional calendrical systems in Chinese-influenced Asian states and territories, particularly those of Japan, Korea, and Vietnam, with the old Chinese system still in use in Taiwan, and to a lesser extent, in Mainland China.