Using the principles of cross-cutting relationships, you can determine the relative age of rocks found in the ground. The idea behind it is that the geologic feature which cuts another is the younger of the two features, and it had been around for 400 years. It's not very precise but it is good for determining relative age.
Answer: Pastoral nomads
Explanation: Pastoral nomads are producers of food, and the size of their tribal or ethnic units increases accordingly. These groups raise livestock, and they move about within their established territory to find good pastures for their animals.
Answer: Tokyo, Japan
south china sea
Sukhbaatar, Mongolia
Philippine Sea
South Pyongan, North Korea