Moreso than either Atlass or Atlantis, the Worlds of Earth very closely resemble each other. In this sense, the Earth of Sigma Prime is much like all the others: a similar history of human civilization populated by alternate versions of the same people.
In this world, the history of central Europe diverged sharply from that of the one you are familiar with. Even more expansive and successful than this world, the Mongol hordes swept through Europe stopped only by the mighty Alps and the heavy weight of their success.
For one hundred years, the Khans ruled the lands stretching from Russia to Germany. And in that time their empire left an indelible mark on the peoples of those lands.
The German principalities after the expulstion of the Khans was a melting pot of politics and religion; Jew, Catholic, Buddhist, and others lived side-by-side. The trade flowing from China, Tibet, and the Hindian kingdoms made its merchants rich and its population diverse.
The Renaissance experienced in Sigma Prime was transcendent, and by the mid-seventeenth century many believed that world peace was a real possibility.
But in this world he Britannic World Empire caused a blight that ultimately could not be undone.