The Otiosian Dispute, also known as the Otiosian Crisis, was the term given to the dispute between the New Republic, the Imperial Remnant, and the Dominion over the control of the Otiosian sector.
The Dominion had claimed the sector as far back as the Clone Wars in 22 BBY, but in the Pelleaon-Gavrisom Treaty of 20 ABY, much of the space was ceded to the New Republic. The Otiosian sector had several resources and strategic worlds which both factions claimed, although the Imperial Remnant had the legal right to much of the habitable worlds. The tensions in the sector escalated when a large rhydonium deposit was found on Otiosia, and escalated further when a New Republic fleet was sent into the area.
The Otiosian sector had long been treasured by all of the major galactic powers for its plentiful resources and it's highly strategic planets.
In international arbitration, the New Republic argued that the region had been part of the original Galactic Republic, and with the Declaration of a New Order, the rights fell to the Imperial Remnant, which had ceded half of the sector to the New Republic in the Pelleaon-Gavrisom Treaty of 20 ABY. Meanwhile, the Dominion based its case the fact that it had claimed the land as far back as 32 BBY, although this claim had long been disputed. The Dominion also pointed out it had occupied much of the planets. Indeed, as of 15 ABY, the Dominion military had claimed 32 star systems.
Furthermore, the discovery of large amounts of Rhydonium, fuel used commonly to power starship engines and reactor cores, was discovered on Otiosia and the surrounding planets. The Dominion had lost almost half of its territory to the Galactic Republic/Empire in the Clone Wars when it sided with the Confederacy and was not prepared to see what it was perceived as its last chance for a viable economy fall victim to the New Republic. Border skirmishes began and grew fiercer and fiercer, until the dispute culminated in an all-out war in 21 ABY with the Dominion attack on Otiosia.