In the history of war from time to time, there are many people who use the scheme "officials and hackers" and transform much. She was trying to lure one or two enemies into the room, "the official of the thieves", really, big, to divide and encircle the enemy in groups, cut off the enemy's way of relief, cut off the withdrawal route, close the door and hit the dogs, tightening the mouth of the enemy bag, such examples were incalculable. In the late Tang dynasty, Thach Kinh Duong joined forces with Khiet Dan and fought Truong Truong Dat in Tan Duong citadel (now Thai Nguyen and Son Tay). Thach Kinh Duong encircled Truong Kinh Dat in an area more than 100 miles long and 50 miles wide.