The Christian world-view in the tenth century was not so very different from ours of today. Then, as now, all sorts of possibilities of when and how the end of the world will come were prophesied.
Anonymous 4 has chosen the Feast of the Ascension, whose liturgy evocatively conjures the Last Judgment, as the basis of their harmonia mundi recording released in the year 2000. On a CD entitled 1000: A Mass for the End of Time, they have assembled a mass drawing mostly on Aquitanian manuscripts from around the year 1000. They enhance some of the written music with the addition of polyphony and drones, as would very likely have been done by singers of the time.
Here is an excerpt from the prose and sequence Salvator mundi/Rex omnipotens, a type of piece that was, in the year 1000, a relatively recent addition to the mass. It’s text rhapsodizes on the coming redemption of the world by the risen Christ.