Sanliqiao II Sanliqiao II sites are located on both sides of the Yellow River in western Henan, southwestern Shanxi and eastern Shaanxi. There are nearly a hundred settlements belonging to this regional variant which show three level settlement hierarchy. The largest site (Xiaojiaokou, 10 km southeast of modern Sanmenxia) is 240 ha in area, whereas local centers range from 30 ha to 70 ha. Dwelling types of Sanliqiao II culture include both aboveground and semi-subterranean type houses as well as homes horizontally dug into loess cliffs with walls frequently coated with plaster. There is noted similarity between the ceramics of this variant and that of the Kexingzhuang II variant. Kexingzhuang II Kexingzhuang II sites are scattered across the Wei River valley in southern Shaanxi. The largest site in this area is 60 ha, which is less than half the size of the largest Yangshao-era site in this region. A population decline is also noted during this period, which scholars attribute to migration caused by environmental changes. Out of 718 identified sites, 25 would be considered "medium sized" centers surrounded by small village settlements in three-level settlement hierarchy. Decline Towards the end of the 3rd millennium BC, the population decreased sharply in most of the region and many of the larger centres were abandoned, possibly due to environmental change linked to the end of the Holocene Climatic Optimum. This was matched by the disappearance of high-quality black pottery found in ritual burials. In contrast, there was a rapid growth of population and social complexity in the basin of the Yi and Luo rivers of central Henan, culminating in the Erlitou culture. The material culture in this area shows a continuous development, through a Xinzhai phase centred on the Song Mountains immediately to the south. In the Taosi area, however, there is no such continuity between Longshan and Erlitou material culture, suggesting a collapse in that area and later expansion from the Erlitou core area. Significance of the discovery of Longshan culture During the 19th and early 20th centuries, there were opposing views on the origin of Chinese culture and civilization: Western origin versus native origin. One of the most representative of “Western Origin” for the culture of prehistoric China was put forward by J. G. Andersson (1874–1960), who excavated the Neolithic site of Yangshao, Henan, in 1921. Many of the unearthed ceramics from Yangshao were painted potsherds. Andersson believed that the