The correct answer is the following.
1.- Korea. The Silla defeated two other kingdoms to unite the country under their rule for centuries.
2.- China. The Sui built the Grand Canal, uniting northern and southern parts of the country but the Tang soon took control.
3.- Japan. A nominal emperor ruled the empire, but warring shoguns competed for power for centuries.
We are talking about moments in the history of ancient Kore, China, and Japan. A time of turmoil and instability due to the ambition for power and control of their rulers and adversaries, that caused problems and blood. These passages of history in ancient Asia show how hunger for power not always is what people need.