What do you guys think of the title ''Out of the Ashes'' refer to?

I think the ''ashes'' part might refer to the burned down Hilltop? The site does look like a pile of ashes now.
But, what does ''out of'' mean?

If we take a common traditional meaning of ''something old destroyed and something new and good comes out'' (eg a phoenix), what good comes out of a destroyed Hilltop?
A pure speculation:- the sparred Whisperer and his few friends get converted and gives some unexpected help when ASZ needs it? Well, his hand got cut off but his life is saved. I think one scene showed his cut off hand in bandage and attended by Carol?