 Sindo was established as a separate county in 1991; previously, it had been part of Ryongch'ŏn, although it had enjoyed a brief existence as a separate county in 1967.Lying in the northwest corner of North Korea, Sindo borders the People's Republic of China to the north and west, and faces the Yellow Sea to the south; to the east, it looks across a narrow expanse of sea at Ryongch'ŏn.Much of the county's land has been reclaimed through draining and filling.