Why was the song ring around the rosy made?

its about the black plague.

ring around the rosy:

means red dots and rings all over your body

a pocket full of posies:

posies are a type of flower; it was said that that was the "cure" for the black plague. i don't think it worked.

ashes, ashes:

every person who died from the disease was burnt to ashes to prevent the plague from spreading.

we all fall down:

everyone died from the plague.