sapiens|humanity]]. It was preceded by the Stone Age (Paleolithic, Mesolithic, Neolithic, and Chalcolithic) and the Bronze Age. The concept has been mostly applied to Europe and the Ancient Near East, and, by analogy, also to other parts of the Old World.
The duration of the Iron Age varies depending on the region under consideration. It is defined by archaeological convention, and the mere presence of some cast or wrought iron is not sufficient to represent an Iron Age culture; rather, the "Iron Age" begins locally when the production of iron or steel has been brought to the point where iron tools and weapons superior to their bronze equivalents become widespread. For example, Tutankhamun's meteoric iron dagger comes from the Bronze Age. In the Ancient Near East, this transition takes place in the wake of the so-called Bronze Age collapse, in the 12th century BC. The technology soon spread throughout the Mediterranean Basin region and to South Asia. Its further spread to Central Asia, Eastern Europe, and Central Europe is somewhat delayed, and Northern Europe is reached still later, by about 500 BC.
The Iron Age is taken to end, also by convention, with the beginning of the historiographical record. This usually does not represent a clear break in the archaeological record; for the Ancient Near East the establishment of the Achaemenid Empire c. 550 BC (considered historical by virtue of the record by Herodotus) is usually taken as a cut-off date, and in Central and Western Europe the Roman conquests of the 1st century BC serve as marking for the end of the Iron Age. The Germanic Iron Age of Scandinavia is taken to end c. AD 800, with the beginning of the Viking Age.
In South Asia, the Iron Age is taken to begin with the ironworking Painted Gray Ware culture and to end with the reign of Ashoka (3rd century BC). The use of the term "Iron Age" in the archaeology of South, East and Southeast Asia is more recent, and less common, than for western Eurasia; at least in China prehistory had ended before iron-working arrived, so the term is infrequently used. The Sahel (Sudan region) and Sub-Saharan Africa are outside of the three-age system, there being no Bronze Age, but the term "Iron Age" is sometimes used in reference to early cultures practicing ironworking such as the Nok culture of Nigeria.