The Nan River originates in the Luang Prabang Range, Nan Province. The provinces along the river after Nan Province are Uttaradit, Phitsanulok and Phichit.
The Yom River joins the Nan at Chum Saeng District, Nakhon Sawan Province.
When the Nan river joins together with the Ping River at Pak Nam Pho within the town Nakhon Sawan it becomes the Chao Phraya River.The Nan river runs about 630 kilometres (390 mi) south.
