Sanmenxia is a prefecture-level city located in the western region of Henan Province, China. It serves as the westernmost prefecture-level city within the province, bordering Luoyang to the east and Nanyang to the southeast. The city also shares borders with Shaanxi Province to the west and Shanxi Province to the north.
Geographically, Sanmenxia is situated on the south side of the Yellow River. It is positioned at a specific point where the river cuts through the Loess Plateau as it travels toward the North China Plain.