Triginta Petra is located in the cluster known as Sigurd's Cradle.
A low-density planet in comparison to Earth, Triginta Petra is also drier, with wide land masses that are largely desert. Its dextro-chirality native life has yet to make it out of the oceans, primarily producing cyanobacteria which provide a limited amount of oxygen in the atmosphere.
A handful of turians colonized the planet and attempted to introduce land plants. Their chief hurdle was the lack of good topsoil, which required imports and sophisticated farming practices to overcome. The farmer’s maxim on Triginta Petra was “if you can last five seasons, you officially known what you’re doing.”
The planet's major enemy was small-time Terminus Systems warlord Rashtek Chass, who extracted tribute from the colonists and any travelers stopping to refuel on helium-3 at neighbouring Nutus. His base was located at Nutus' moon Etrat.
The Reapers judged the planet's population too low to harvest and struck its colonies with kinetic impactors. They then moved on, trusting that the destruction of the food supply’s main arteries would finish off the inhabitants of such a biota-poor world. They presumed wrong, as most of its colonists still live, buoyed by supply drops conducted by none other than Rashtek Chass. Still, this had its catch, and Chass doesn't expect his charity to go unrewarded; the planet has been pressed into a number of tithes to the warlord under a pretense of repaying a significant debt.
Incidentally, recovered rations from Triginta Petra played their own part in the Reaper War. Several on-planet agribusinesses had a surplus of food products for dextro-based sapients. Both turian troops, who favour a meat-heavy diet, and their quarian allies, who are typically vegan, showed a marked preference for these recovered rations, suggesting that although they suffered great losses, the Petrans at least had pretty good taste.