Something I noticed in Silentium description

“The Precursors created many technological species, including Humanity and the Forerunners. But the roots of the Flood may be found in an act of enormous barbarity, carried out beyond our galaxy ten million years before…”
What could this mean? This seems very interesting and mysterious, do you agree?

Truly no clue, but I’m guessing it has something to do with the Forerunners and Precursors, or perhaps just the Precursors. I was really hoping H4 would lay some groundwork but I’ve yet to come across any yet.

I assume the act of barbarity is referring to the forerunners rising up and destroying the Precursors. The Timeless One hints that the flood were the Forerunners punishment for this.

Maybe the backstory to the Flood’s creation and what the Precursors did?