What is the setting of To Your Scattered Bodies Go; a Science Fiction Novel by Philip Jose Farmer?

The majority of the story takes place on the new planet inhabited by the resurrected humanity. The planet is covered by a river millions of miles long that snakes and wraps around it in such a way that it begins very close to where it ends. On the shores of either side of the river are grasslands, and grailstones are placed at regular intervals along the length of the river. As one goes farther from the river, the terrain eventually turns into hills, and then mountains with a climate too difficult to pass over. The land along the river itself has a generally uniform climate, which is warm and mild.