They are not back dating their birth years. They are actually writing their birth years using the Republic of China Calendar. 1912 was the first year of the founding of the Republic of China. Therefore, 1912 was Year 1 of the Republic of China.As you might know, the Republic of China retreated to Taiwan in 1949. In Taiwan, people still write their birth dates on official documents using the Republic of China Calendar. A person born on 1 January, 1970, would write oneu2019s birth date as the 59th year of the Republic of China, January, 1.