mass extinction event

Joab is a two-mooned habitable planet that is most well known for its mass extinction event. Thousands of years ago, Joab was home to a primate-like spacefaring civilization as well as abundant flora and fauna. However, this can only be deduced from time capsules put into the ground well outside habitation centers -- all cities and detectable dwellings were targeted in a massive orbital bombardment that turned them into vapor. The resulting dust shroud killed all photosynthetic life and all fauna dependent on it.