An even longer river which flowed through Wu-chou to Canton was the Pearl. One level 3b city, Nan-ning fu, and two level 4 cities, Hsün-chou fu and Kuei hsien, served as ports en route to Wu-chou. The other level 3b city, Liu-chou fu, was located on a tributary of the Pearl river in an area from which lumber was sent to Kwangtung. Together with rice from Hsün-chou fu and Nan-ning fu, lumber and other products from the mountains sailed downriver to Wu-chou.