Complex sentence: Although the population decreased overall on the peninsula, the use of tools increased significantly during this time; artifacts have shown that these people used drills, knives, choppers, atlatls, and awls made from stone, antlers, and bone.
Split into simpler sentences: Although the population decreased overall on the peninsula, the use of tools increased significantly during this time. Artifacts demonstrate that these people used drills, knives, choppers, atlatls, and awls made from stone, antlers, and bone.