Ahn was born Ahn Ch'i-sam, on the 6th day of the 10th lunar month 1878 in Kangso County, Pyeongan province, in present-day South Pyongan, North Korea. His birth date is equivalent to 10 November 1878 on the Gregorian calendar but he chose to use the date 9 November 1878 on his vita. "Ahn" is the family name, "chi" is the generation marker, and "sam" refers to the fact that he was the third son of Ahn Kyon-jin (father), and Hwang (Mother). Dosan is of the family of the Sunheung Ahn (순흥안씨; 順興安氏) lineage.