Archaeology
The city of Teotihuacán falls to unknown invaders about this time, after 150 years of decline. See also 100 ce Construction.
ChemistryArabic alchemist Geber describes how to prepare aluminum chloride, white lead, nitric acid, and acetic acid. See also 300 ce Chemistry; 900 Chemistry. (See biography.) (See essay.)
CommunicationThe Hohokam people living in what is now New Mexico discover etching; by covering part of a shell with pitch and exposing the rest to acidic cactus juice, they etch decorations into the shells. Etching will be rediscovered in Europe in the 15th century.
ConstructionThe Anasazi leave their pit houses at least in summer and move into masonry buildings that consist of long lines of rooms that face the old pit houses. Different rooms in the masonry houses are used for different purposes, such as sleeping, cooking, or storage. The pit houses may be retained for ceremonial use simply because they are warmer than the row houses in winter. See also 600 Construction; 800 Construction.
MaterialsIn Egypt, the practice of using a thin film of a metal oxide, called a luster glaze, is developed for use on glass, although glazes will become common only when adapted for use on pottery. See also 850 Materials.
