All macroremain samples from the Nagqu area yielded negative radiocarbon ages. The atmospheric nuclear weapon tests in the 1950s and early 1960s caused a steep increase of atmospheric 14C production to nearly double the natural value in 1963, leading to 'hyper-modern' 14C contents in naturally produced organic material, thus to highly negative radiocarbon ages. Thus the radiocarbon ages of the macroremains analysed can be clearly identified as modern (after 1950).