3 One of the most significant short-term results of the settlement of the Great Plains was –

Increased miles of railroad track and population helped settle the plains. ... Railroads charged Plains farmers a higher fee than they did farmers in the East; they charged more for short hauls and forced the farmers deeper into debt.

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.