The Kingdom of Oshurin was established some 500 years ago by the conqueror-king Hastar. Hastar united the lords of the south lands together and invaded the rich lands north of the river. He drove back the inhabitants of the land, the Cor, beyond the Hallowed Hills where they established their own Kingdom of Corandol.
Currently Oshurin is ruled by King Adumir. Adumir is not a warrior and has let the army and defenses of the kingdom fall into some disrepair. This has allowed Corandol to be openly aggressive towards Oshurin. The tension that this causes just recently erupted into an all out war.