The Iron Age is the most recent period in the three-age system in archeology for classifying human prehistory. It began in about the 12th century BC in the Near East, India, and Greece, the 8th century BC in most of Europe, and the 6th century BC in Northern Europe. This age ended in the 4th or 5th century BC in most of the world, but as late as AD 500 in Northern Europe.
As the name implies, the Iron Age refers to the period of time when ironworking was the most sophisticated type of metallurgy. Ironworking is preferable to the bronze working which preceded it due to the higher durability and availability of iron ore. An civilization in the Iron Age coming into contact with a Bronze Age civilization would have a huge advantage through its weapons. An iron sword could break a bronze sword with a strong blow.
The first systematic production of iron began in Anatolia in what is modern-day Turkey, and spread to both the East and West simultaneously. Anatolia was the center of the Hittite Empire, who used iron weapons to conquer large parts of the Near East. Their writing system was based on cuneiform, like the Babylonian culture before them. They spoke an early Indo-European language.
Housing in the time of the Iron Age was based around grass huts. Agriculture was very well established, and thousands of years of selective breeding were paying off, not only with plants but also livestock. Instead of being based around small tribes, nation-states and true nations existed, with an often tenuous central control and an expansionist bent. The whole non-polar world was inhabited by humanity except for Madagascar, Iceland, and New Zealand.
In the Iron Age, much of the world was still occupied by hunter-gatherers and nomads, including the Americas, most of Africa, and Australia. The majority of Asia and Europe were steeped in this age, with non-nomadic cultures throughout these continents.