River Song's World

River Song's World was an alternate timeline created by River Song when she interfered with a fixed point in time, namely the death of the Eleventh Doctor. In this timeline, time itself had begun to unravel. All of Earth's history occurred simultaneously.

History
River Song prevented the "death" of the Eleventh Doctor, which occurred on April 22, 2011 at Lake Silencio, Utah. River, knowing that Madame Kovarian had forced her to assassinate the Doctor, had drained her suit of power.

At the "time" of the restoration of the normal timeline War of the Roses had entered its second year, Pterodactyls flew through the air and Winston Churchill was the Emperor of the Holy Roman Empire.

Churchill was able to sense that something was wrong because the time and date never changed. Churchill had the Doctor, known in this world as a soothsayer, brought to him and demanded he explain why the time never changed. After revealing how this timeline was created, the Doctor and Churchill were attacked by the Silents only to be rescued by a group of soldiers led by the alternate Amy Pond. The alternate Amy Pond remembered certain things about her travels with the Doctor in the original timeline, but initially couldn't remember that Rory Williams (one of her soldiers) was her husband or that River Song was their daughter.

This alternate timeline was ended when the Doctor convinced River Song to make physical contact with him (in the form of a kiss). Because she and the Doctor were the opposite poles of the disruption in time, their touching caused time to revert to its original state, where River "killed" the Doctor.