Once a vast plain, trickling streams have turned into great rivers and carved out the land, leaving long islands between land masses. These are the only paths leading to the others.
You have just found this land, so you have sent some explorers to find out what is around. you sent out 5 of them, and only one returns. He brings a map showing one island in the center of the land rich with resources. But when you ask what happened to the others, he simply crys.
After the "episode", he explains there are two other nobles already deep into war. You will have to deal with them.