4.2-kiloyear eventThe 4.2-kiloyear (thousand years) BP aridification event (long-term drought) was one of the most severe climatic events of the Holocene epoch. It defines the beginning of the current Meghalayan age in the Holocene epoch. Starting around 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area.
Obsidian use in MesoamericaObsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica. Obsidian was a highly integrated part of daily and ritual life, and its widespread and varied use may be a significant contributor to Mesoamerica's lack of metallurgy. Lithic and contextual analysis of obsidian, including source studies, are important components of archaeological studies of past Mesoamerican cultures and inform scholars on economy, technological organization, long-distance trade, ritual organization, and socio-cultural structure.
Olmec colossal headsThe Olmec colossal heads are stone representations of human heads sculpted from large basalt boulders. They range in height from . The heads date from at least 900 BC and are a distinctive feature of the Olmec civilization of ancient Mesoamerica. All portray mature individuals with fleshy cheeks, flat noses, and slightly-crossed eyes; their physical characteristics correspond to a type that is still common among the inhabitants of Tabasco and Veracruz. The backs of the monuments often are flat.
Naqada cultureThe Naqada culture is an archaeological culture of Chalcolithic Predynastic Egypt (c. 4000–3000 BC), named for the town of Naqada, Qena Governorate. A 2013 Oxford University radiocarbon dating study of the Predynastic period suggests a beginning date sometime between 3,800 and 3,700 BC. The final phase of the Naqada culture is Naqada III, which is coterminous with the Protodynastic Period (Early Bronze Age 3200–3000 BC) in ancient Egypt.
Erligang cultureThe Erligang culture (er4.li3.gang3) is a Bronze Age urban civilization and archaeological culture in China that existed from approximately 1600 to 1400 BC. The primary site, Zhengzhou Shang City, was discovered at Erligang, within the modern city of Zhengzhou, Henan, in 1951. The culture was centered in the Yellow River valley. In its early years, it expanded rapidly, reaching the Yangtze River. The culture then gradually shrank from its early peak.
Mesopotamian MarshesThe Mesopotamian Marshes, also known as the Iraqi Marshes, are a wetland area located in Southern Iraq and in southwestern Iran. The marshes are primarily located on the floodplains of the Euphrates and Tigris rivers bound by the cities of Basra, Nasiriyah, Amarah and a portion of southwestern Iran. Historically the marshlands, mainly composed of the separate but adjacent Central, Hawizeh and Hammar Marshes, used to be the largest wetland ecosystem of Western Eurasia.