[4] Houaysouy was a Hmong village in Sainyabuli that had no fighting during the Laotian Civil War, and Vang Pao did not recruit any of its men.

After the war, Anne Fadiman, author of The Spirit Catches You and You Fall Down, said that the village was "tossed into the political melee along with the rest of the country."

The province is mountainous with the Luang Prabang Range running roughly in a north–south direction and forming a natural border with the Thai highlands.

Hill ranges reach a maximum elevation of 1,790 metres (5,870 ft), and are part of the Luang Prabang montane rain forests on the Thai border.

[12] The protected area was identified by the Government of Laos in the National Elephant Conservation Meeting held in 2008 and WWF has been in the forefront in this effort since 2005.

[20][21] The 10,980 hectare Upper Lao Mekong Important Bird Area (IBA) stretches across the provinces of Sainyabuli, Bokeo, and Oudomxai.

The topography is characterized by river channel, exposed beds, sandbars, gravel bars, islands, rock outcrops, bush land, and braided streams.

Notable avifauna include black-bellied tern (Sterna acuticauda), great cormorant (Phalacrocorax carbo), grey-headed lapwing (Vanellus cinereus), Jerdon's bushchat (Saxicola jerdoni), brown-throated martin (Riparia paludicola), river lapwing (Vanellus duvaucelii), small pratincole (Glareola lactea), and swan goose (Anser cygnoides).

Recorded avifauna include wire-tailed swallow (Hirundo smithii), small pratincole (Glareola lactea), river lapwing (Vanellus duvaucelii), Jerdon's bush chat (Saxicola jerdoni), and the great thick-knee (Esacus recurvirostris).

[25] Other ethnic groups are the Khmu, Tai Dam, Htin, Phai, Kri, and Akha; the Malabri, who reside in the forests of western region of the province, are the last hunter-gatherers in Southeast Asia.

Other important crops include maize, oranges, cotton, peanuts, sesame, sugarcane and vegetables such as cucumbers, cabbage, and beans.

[9] Some of the unique features of these landmarks are the Tai Lue villages where traditional houses are still built with high-sloping roofs, the Tai Lue style temples of Vat Ban Khon which depict rare natural fiber murals and decorations, Vat Si Phan Don known for its diamond-shaped stupa, and French colonial buildings, traditional Lao-style wooden houses can be seen in the Pak Lay town on the banks of the Mekong River, which lies between Vientiane and Sainyabuli.