On this world, a single large ocean spans much of the northern hemisphere. There are many smaller lakes and seas confined within circular craters, connected by rivers and canals. Much of the land is covered by dark green forest and by broad, sweeping grasslands and steppe.
But ice is gathering at the poles. The oceans and lakes are crawling back into great underground aquifers. Soon the air will start to snow out.
The grip of the ice persisted for billions of years before being loosened, it seemed forever. And yet it comes again.
This is the Sky Steppe.
This is Mars.
The time is three thousand years after the birth of Christ. And in all this world there is no human to hear the calls of the mammoths.