Complex sentence: The Lower Kootenay region is, as mentioned above, remarkably rich in fish, birds, and large game, and so the economic life of the Yaqan Nu’kiy was notably secure, and thus resistant to new unfamiliar economic activities.
Split into simpler sentences: The Lower Kootenay region is, as mentioned above, remarkably rich in fish, birds, and large game. As the economic life of the Yaqan Nu’kiy was notably secure, they resisted new and unfamiliar economic activities.