Haas notes the absence of any suggestion of physical bases of power, that is, defensive construction. There is no evidence of warfare "of any kind or at any level during the Preceramic Period". Mutilated bodies, burned buildings, and other tell-tale signs of violence are absent, and settlement patterns are completely non-defensive. The evidence of the development of complex government in the absence of warfare is in marked contrast to archaeological theory, which suggests that human beings move away from kin-based groups to larger units resembling "states" for mutual defense of often scarce resources. A vital resource was present: arable land generally, and the cotton crop specifically, but the move to greater complexity was apparently not driven by the need for defense or warfare.