In what way did 9/11 change the valley?

Chapter 3 ends with Malala recounting the events of September 11, 2001 (which took place when she was four years old), saying that they changed her valley forever. The Taliban created more of a hold in the valley and the West, especially America, was enemy number one.

9/11 have changed valley a lot because many people talk about it. Taliban terrorists are responsible for this action, there a lot of them in the valley.