In the Edo period, Koishikawa included areas not only around the Koishikawa Village in Toshima County, Musashi Province but also the areas from the Kanda Josui (Kanda water supply), which is the current Suidobashi Station area, to Hakusan (Bunkyo Ward).
江戸期には、武蔵国豊島郡(武蔵国)小石川村のみならず、神田上水の現・水道橋駅界隈から白山(文京区)あたりまでを含む広い地域を指す呼称であった。