横向
1
Period of one hundred years
3
Period of ten years
7
Belonging to a very old period
8
Object made by humans from the past
9
Government ruled by a king or queen
纵向
2
Person owned as property
4
Ancient Mesoamerican civilization
5
Military conflict or fight
6
Alloy of copper and tin used in early tools
10
Exchange of goods between peoples
11
Advanced stage of human society
12
Metal that replaced bronze in tools