What Happened To All The Lantern Corps?

One of the oldest existing Lantern Corps outside of the Green Lanterns, the Orange Corps - who's powers revolve around greed and avarice - are infamously initially revealed through stories of a great war between the Guardians and the Keeper of the Orange Light, held millenia ago.

The war concluded by allowing the Keeper - known now as Larfleeze, leader of the Orange Lanterns - to keep his territory without Green Lantern interference, so long as the Orange Light and the battery that powered it was kept concealed underground.

When the battery was almost stolen, the Orange Lanterns came back out of this hiding. After a further war with the Orange Lanterns, the Guardians converge on the Orange Light, ready to destroy it for once and for all. This fails, showing us the insane power levels the Orange Light contains, and setting up the fight between the Blue and Orange Lanterns that starts Blackest Night.

Larfleeze does join the Blackest Night fray, but only after being promised his own personal Guardian after the war - a promise that is fairly broken after the murder of all but two of the Guardians.