series of sedimentary units overlying them. As these blocks have been fused together, the oceans that once separated them have been compressed into the orogenic belts, that are now between them. There are multiple ways of naming and defining each of these units in the modern literature. North China Craton The Precambrian North China Craton is predominately metamorphosed island-arc igneous rocks that formed between 3.5 and 3 billion years ago. The craton had fully formed by 1.7 billion years ago. Thick sediments were deposited on the craton from 1000 to 539 million years ago. South China Craton The South China Craton (also Yangtze Craton) is younger than the North China Craton and ranges in age from 2.5 to 0.8 billion years old. The South China Craton is divided into three parts, western, central and eastern. Unlike the North China Craton the South China Craton used to be part of Gondwana. The Cathaysia Fold Belt is attached to the southeastern side of the Craton. Tarim Block The Tarim Block in North West China (Xinjiang) is a relatively thin zone of Precambrian rock and Neoproterozoic to Cambrian cover sequence that may be related to the South China Craton. The Precambrian units, like the South China Craton, also finished forming 0.8 billion years ago. The Tarim Block can be divided into three parts the North Tarim, South Tarim and Central Tarim terrane. Between 2.80 and 2.57 billion years ago the Tarim Block was intruded by granites. During the formation of the Columbia and Rodinia supercontinents the block experienced tectono-metamorphic events between 2.0–1.8 and 1.0–0.9 billion years ago respectively. From 760 million years ago the Tarim Block began to split from Rodinia leading to igneous activity. Following this a series of terranes were accreted to the side of the block. In the early Paleozoic the Qaidam was accreted to the south and in the late Paleozoic the Yili Terrane was accreted to the north of the block. Igneous activity finished in the block, after the formation of a large igneous province in the Permian. Himalayan Orogen The Tethys Ocean closed about 50 million years ago and Indo-Australian Plate began to collide with Asia. The Himalaya is now mostly formed from the uplifted sedimentary rocks from this ocean. These sedimentary rocks along with associated igneous rocks, now often metamorphosed, from a series of east–west slivers of rock through the mountain range. From south to north