第一个句子改为正确语序应该是Teotihuacán’s geographic location on a natural trade route to the south and east of the Valley of Mexico,the obsidian resources in the Teotihuacán Valley itself,and the valley’s potential for extensive irrigation are among the main factors.
所以它用倒装的前提是主语太长,而表语太短,正常语序句子不平衡.而第二个句子其实不符合这个条件,所以改成倒装句并不怎么合适.