How did they mark houses with plague victims black plague?

A red cross on the door.

Explanation:

I learned about this in 2nd grade

what is the "this" there is no picture

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.