Dunhang Block is located between the North China and the Tarim Cratons (Figure). It is bounded by the Beishan Orogenic Belt to the north and Altyn Tagh Orogenic Belt to the south, respectively; in the west the Qiemo-Xingxingxia fault separates the block from Tarim Craton, and in the east the Altyn Tagh Fault separates it from the Alxa block of western part of the North China Craton. Although Archean-Paleoproterozoic basement rocks, which are referred to as Milan Complex, exposed along the Northern Altyn Tagh Orogenic Belt, some researchers suggested that their rock associations, metamorphisms and evolutionary history present obviously different with those of the Dunhuang Complex in Dunhuang region, Gansu Provence, thus the Milan Complex should be excluded from the Dunhuang Block, and is considered as basement rocks of the southwestern Tarim Craton.