Lying within the traditional territory of the Niitsítapi (Blackfoot: Kainai, Piikáni and Siksika), Writing-on-Stone / Áísínai'pi ("it is pictured/written") is a sacred place where geological formations house spirit beings, and more than 85 rock art localities record the "writings" of the spirits. The proposed nominated property, 1 718-hectares of Writing-On-Stone Provincial Park (Áísínai'pi National Historic Site) in the Milk River Valley, is a spectacular pocket in the mixed grass prairie landscape sweeping through south-central Alberta to the powerful Kátoyissiksi (Sweetgrass Hills, Montana, USA). Defined by the valley's eroded ancient sandstone cliffs, it is characterized by dramatic views, eerie light and sounds, hoodoo formations, adjacent coulees and prairie habitats rich in mammal, bird and plant species. For at least 4 000 years, Aboriginal people have stopped here in the course of their seasonal round. The petroglyph and pictograph sites on the valley walls include several thousand motifs in hundreds of scenes, predominantly anthropomorphs, zoomorphs and material object motifs. Ceremonial and ritual figures, exploits of hunters and warriors, and diverse animals are depicted among the images. New motifs created after European contact in the early 18th century include guns, horses and dynamic human figures, the instruments of Aboriginal-Euro Canadian contact and cultural change. Burial places, vision quest locations and a medicine wheel on the rim of the valley also mark the spirituality of the landscape. Traditional knowledge describes the origins and history. A reconstructed North West Mounted Police post sits on the site of the original post. The Niitsítapi identify Kátoyissiksi (located in the USA) as an integral part of the cultural landscape, and their prominence within the viewshed of Writing-on-Stone / Áísínai’pi contributes to the overall integrity of the proposed nomination property.