In The Time of the Doctor, the Silence of seasons 5-6 are revealed to be a splinter group from The Church. This splinter group went back along the Doctor's personal timeline and tried to prevent him from going to Trenzalore. So why did they also control Earth's history for thousands of years? In The Time of the Doctor it's stated that their goal was purely to stop the Doctor from reaching Trenzalore, but controlling Earth doesn't seem to further that goal.
Why did the Silence interfere with or guide Earth history?