Final answer:
The Pacific northwestern tribes were not known for their agriculture; this statement is false. They mainly relied on hunting, gathering, and especially fishing, which shaped their rich cultural and social practices, including the potlatch ceremony.
Step-by-step explanation:
The statement that the Pacific northwestern tribes were known for their agriculture is false. The tribes of the Pacific Northwest, including well-known groups such as the Tlingit and Haida, supported themselves primarily through hunting, gathering, and fishing, with a particular emphasis on salmon fishing. These methods were due to the region's rich natural resources, which provided a high carrying capacity and allowed for large, permanent towns that became the political structures of these societies. The Pacific Northwest was known for its complex societal hierarchy and the practice of potlatch, which reinforced the social structure.