These are four of the most important requirements of what religion?

When did Feudalism begin before the period?

Origins of the idea. The terms feudalism and feudal system were generally applied to the early and central Middle Ages—the period from the 5th century, when central political authority in the Western empire disappeared, to the 12th century, when kingdoms began to emerge as effective centralized units of government.

Explanation:

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer