9/11 incident took place in which era of?

9/11 incident took place in which era of?

Explanation
 9/11 refers to the terrorist attacks on September 11, 2001 in the United States.

At that time, General Pervaiz Musharraf was the President of Pakistan (he took power in 1999 through a military coup and remained until 2008).
The September 11 attacks, commonly known as 9/11,
They were four coordinated Islamist terrorist suicide attacks by al-Qaeda against the United States in 2001.