One can imagine the axis of such a world being explosively shifted, disastrously, perhaps even accidentally, producing lethal, global tumults of storms and climates. One might speculate on mines capable of blasting continents into orbit, and, then, consequent upon diminutions of mass, oceans being sucked away into space. Perhaps, too, the world as a whole was literally fragmented, broken into hundreds, perhaps thousands, of irregular, tumbling planetoids incapable of holding an atmosphere. Or perhaps its orbit was explosively affected, merely hurling it too close or too far from its primary, exiling it from a habitable zone. Or perhaps there was a braking of its rotation, perhaps suicidally intended, designed to produce two hemispheres, one a world of unrelieved light and heat, a scalding, furnacelike world, the other a world of perpetual darkness, a silent, polar waste. Perhaps, on the other hand, there was merely a radiological sterilization of the world, perhaps one rendering it progressively incapable of supporting life.

Whatever the particular stimulus or etiology of their migration, the Kurii long ago left their world. They may have voyaged for generations. But it is possible, too, they did not have so far to go. They currently inhabit a set of steel worlds, perhaps hundreds of them, mingled within, shielded within, what we, or you, I suppose, call the asteroid belt. The asteroid belt is perhaps the debris of what was once a planet. It is not impossible, though I do not think it likely, that it is the debris of what was once the planet of the Kurii.

Though it might once have been the world of a similar species, an animal capable of, say, destroying its habitat, of rendering itself extinct.

Such species doubtless exist. Perhaps you are aware of one.

Even the fiercest of enemies may upon occasion unite in a common project, willing to suspend their inveterate hostilities in order to achieve a common goal, say, that of discovering and acquiring a world suitable for the purposes of their life form.