The people of southwest coast of British Columbia (including the people from Kosapsom site) became known as 'Northern Straits'. The 'Northern Straits' people were further sub-divided into several groups: Sooke (around Sooke Harbour), Songhees / Esquimalt (around Victoria), Saanich (Brentwood, Patricia, Saanichton), Semiahmoo (Mainland around Semiahmoo Bay), Lummi (Hale Passage) and Samish (Samish and Guemes islands). Kosapsom is in the Songhees / Esquimalt territory.

At Kosapsom, subsistence revolved around fishing, hunting and gathering. Men were responsible for hunting, fishing and warfare while women's roles were to gather fruit, vegetables and shellfish. Women were also given the task of food preservation by drying or smoking. The most important natural resources that were exploited includes, salmon, herring, shellfish, marine mammals and land animals. Food was gathered seasonally and preserved. Vegetables and fruits were less abundant than the shellfish but provided enough nutrition to balance the meat consumption. The surrounding hills were abundant with cedar trees, and the trees were used to make mats, baskets, clothing, houses and canoes. The climate was mild much like it is today.

In 1850, the Colonial Government acquired Kosapsom and in 1853/54 the Craigflower schoolhouse was built. The schoolhouse was used until 1910 and then shortly after, the building was restored by the Province as a heritage attraction.

Harlan Smith (1907:pg.355) noted that in the late 1890's, the north side of the Gorge from Tillicum Bridge to Admiral's bridge, there was a "continuous shell ridge, composed largely of pure shell material". Most of this shell ridge has been obliterated and cannot be seen today because of the Gorge Waterway Project, which included the construction of a sea wall, walkways and extensive landscaping. However, the archaeological site lies beyond the boundaries of the Gorge Waterway Project and therefore the stratigraphy is relatively undisturbed.