China’s first test, in the province of Xinjiang in western China was conducted at the Lop Nur test site in the Gobi desert, close to the ancient Silk Road, in 1964. Three years later China detonated its first hydrogen bomb, among the further 45 tests conducted at Lop Nur: 23 were in the atmosphere and 22 underground. China was the last of the five nuclear weapon states to be recognised under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).