He was a young boy when come to the throne of france; his royal minister was cardinal mazarin

Louis XIV (the 14th)

Explanation:

He got on the throne at age of 5, at the death of his father (Louis XIII).

His reign lasted 72 years... more than any other King of France and one of the longest in history of the world.  He was nicknamed Le Roi Soleil (the Sun King), because of its longevity.

Elizabeth II of England has now done over 67 years, to give you a reference point.

1. it was caused by feudalism

2. charlemagne used christianity as a major cornerstone for his rule. cloisters were built all over the empire to act as centers for the (re)population of the vast european wilderness.

3. the europeans feared the next raid every time chetak

i'm not so sure about #6. but i hope i you with the first 3.