Final answer:
The cornerstones of the feudal system were land and military. The fall of the Western Roman Empire led to an era of tribal warfare and political instability.
Step-by-step explanation:
Question 4:
The two things that were cornerstones of the feudal system were land and military.
Question 5:
The event in European history that led to an era of tribal warfare and political instability was the fall of the Western Roman Empire. After the fall of the Roman Empire, Europe was divided into smaller territories ruled by feudal lords, leading to power struggles and conflicts.
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