en_tn_condensed/exo/12/51.md

It came about

This phrase is used here to mark an important event in the story. If your language has a way for doing this, you could consider using it here.

by their armed groups

The term used for these groups is a military term referring to a large number of soldiers. See how you translated "armed group" in Exodus 12:17. AT: "by their divisions" or "by their regiments"