In a strict sense, wasan refers to mathematics developed by Takakazu SEKI that flourished during the Edo period, but in a wider sense, it refers to mathematics in general practiced and studied in Japan before the introduction of mathematics from Europe.
狭義には大いに発展した江戸時代の関孝和以降のそれを指すが、西洋数学導入以前の数学全体を指すこともある。