Traditional Chinese years were not continuously numbered in the way that the BC/AD system is. More commonly, official year counting always used some form of a regnal year. This system began in 841 BC during the Zhou dynasty. Prior to this, years were not marked at all, and historical events cannot be dated exactly.
In 841 BC, the Li King Hu of Zhou was ousted by a civilian uprising, and the country was governed for the next fourteen years by a council of senior ministers, a period known as the Regency. In this period, years were marked as First (second, third, etc) Year of the Regency.
Subsequently, years were marked as regnal years, e.g. the year 825 BC was marked as the 3rd Year of the Xuan King Jing of Zhou. This system was used until early in the Han dynasty, when the Wen Emperor of Han instituted regnal names. After this, most emperors used one or more regnal names to mark their reign. Usually, the emperor would institute a new name upon accession to the throne, and then change to new names to mark significant events, or to end a perceived cycle of bad luck. In the Ming and Qing dynasties, however, each emperor usually used only one regnal name for their reign.
This sytem continued until the Republic of China, which counted years as Years of the Republic, beginning in 1912. Thus, 1912 is the 1st Year of the Republic, and 1948 the 37th. This system is still used for official purposes in Taiwan. For the rest of China, in 1949 the People's Republic of China chose to use the Common Era system (equivalently, AD/BC system), in line with international standards.