May 29, 1382, April 16 (Saigon), the emperor set up the Guard. 29 (

1382 speak Ming Wu fifteen years April 16), the emperor set Guard. It was originally guarding the palace of the pro-military, in charge of the emperor out people ceremonial. The first Ming strengthen authoritarian rule, the extension of the powers of the Guard's also responsible for Criminal Prison, reconnaissance, and arresting thieves Jiandang, monitor Wenwubaiguan. Supreme Executive of command so often by the hero, the wife's family act, Let TongZhi, official corporate thing, under which a government school, specially reconnaissance. The Guard belongs lock ask the Secretary of the north and south two North Zhenfu Division designed and Zhao Yu, taken directly aims to act is particularly severe and cruel torture. Guard massacred civil and military ministers, repression of people everywhere, to cook up a big prison, very public arrests. Further strengthen the reign of Yongle Emperor Zhu Di, the Guard's spies nature.
1420 they erected Dongchang. In 1477, Ming Xianzong more set West plant. The Emperor Wuzong and additional expert plant, the collectively the plant guard system, creating a spy system of the first of its kind in China.