The Iron Age

Iron: The Origin Story

Word reaches your village slowly. The king’s army has been defeated, and the invaders are headed your way. They have weapons that seem many times more deadly than your own. Their soldiers are armed and armored with a strange new technology. Even worse, they outnumber your people. Their advanced technology allows them to sustain larger populations and reshape the world around them. As they swarm along the rivers of Mesopotamia, they leave the burnt remains of forests behind them. But these are not supernatural invaders. They’re humans, and they have learned to harness the most common metal on Earth: iron.

Early human history is usually studied in three periods: the Stone, Bronze, and Iron Ages. Historians periodize early human history in this way because tools made of hard materials like metal and stone are often the only remnants from these ancient societies. It varies by region, but this periodization is most accurate when we are talking about Afro-Eurasia.

The Iron Age lasted roughly from 1500 BCE to 500 BCE. We’re used to iron now, but iron-making technology was a major innovation, and it took thousands of years for people to figure it out. Smelting¹ bronze wasn’t exactly easy either, so let’s compare. To make bronze, you combine tin and copper, melting them at about 950 degrees Celsius. Early humans could do this in a pottery furnace. Iron needs a furnace that can handle 1,538 degrees Celsius—way too hot for a pottery furnace. A big advantage with iron was that you only need one metal, which is much easier to get than copper or tin.

The timing of the first iron-smelting technologies is significant. Several major states in the Eastern Mediterranean began to collapse around 1200 BCE, the Late Bronze Age. Egyptian, Greek, and Hittite cultures all faced a crisis. Several different factors caused this collapse, including earthquakes, droughts, and invasion by a mysterious group known as “Sea Peoples.” The introduction of iron technology, combined with this collapse, rapidly changed the ancient world into something that began to look a lot less ancient. In the wake of ecological catastrophe and invasion, iron reshaped regional power dynamics, trade networks, natural environments, and human social orders from the Mediterranean to China.

Swords into Ploughshares: Iron Reshapes Power Dynamics

When we talk about the Iron Age, we usually picture swords, but that’s not really what made iron technology so powerful. Sure, iron weapons are stronger than bronze, but the real advantage is that iron is easier to make. It all comes down to the chemical composition of the Earth. Iron is the most abundant metal on our planet, so it’s easy to get your hands on.

The copper and tin needed to make bronze are hard to find, and not always found in the same area. States using bronze technology to outfit their armies were dependent on trade to obtain one or both metals. When war or a large-scale disaster like the Late Bronze Age collapse disrupted trade, they couldn’t make weapons and tools. Meanwhile, societies that solved the high-temperature furnace problem were able to grow much stronger as the Iron Age began. Suddenly they could make more tools and weapons faster and cheaper.

More Ore: Iron Reshapes Trade Networks

Ancient Eurasia was interconnected and interdependent during the Bronze and Iron Ages. Wars and trade connected the Eastern Mediterranean to Western India and the lands in between. Armies and merchants brought bronze and iron technologies along these trade networks over several centuries. Communities in world zones outside these networks, such as the Americas and the Pacific Ocean, were left out of the Iron Age transformations. These zones would not use iron technology until the sixteenth century CE.

The earliest evidence of extensive iron smelting comes from the Hittites, who ruled an empire in Anatolia from around 1500 BCE to 1177 BCE.

Iron smelting technology gradually spread from Anatolia and Mesopotamia across Eurasia. By around 1000 BCE, Indian farmers needed more rice paddies to feed the growing number of people in new cities. So they used iron tools to clear the forests around the subcontinent’s great rivers to make room for rice. By 700 BCE, people in China adopted iron smelting technology, innovating iron production by developing larger, even hotter furnaces capable of melting iron to a more liquid state. That meant it could be poured into molds, a method known as cast iron. This type of metal was too brittle for weapons, but it was excellent for making cheap iron plows, tools, pots, and art. An abundance of cast iron tools allowed Chinese farmers to increase and intensify agricultural production. More food led to rapid population increases in China, just as iron technology had done in Mesopotamia and India.

There is evidence to suggest that iron-smelting technology developed independently in sub-Saharan Africa around the same time that the Hittites began working with the metal. In Central Africa, several communities were already connected by the Bantu² language. But it was iron that allowed them to clear African forests and spread their agricultural societies across a region larger than the United States.

Turning Trees into Swords: Iron Reshapes the Environment

Humans have always impacted the environment, but Iron Age societies reshaped the world around them in unprecedented ways. Iron smelting furnaces needed lots of fuel. The most abundant and hottest-burning fuel available to ancient societies was wood.

Once people started using iron tools, they became dependent on increased productivity to sustain growing populations. That meant more crops needed to be planted. So, they cut down more trees to, 1) make larger fields and, 2) use the wood to fuel their furnaces. More wood meant they could smelt more iron and feed even more people. Even more people meant they needed more iron tools, which required—you guessed it—more wood. Armed with new iron axes, farmers set out to harvest more trees and clear more land. Soon, forests started to disappear. For most of human history, populations increased only gradually. The Bronze and Iron Ages kicked off a population boom for ancient human communities.

Iron Forges Social Relationships

As iron helped populations grow, empires extended their reach over larger territories. By 800 BCE, the Assyrian Empire dominated Mesopotamia with an army of 200,000 soldiers. Sustaining such a large army was only possible with an efficient government and iron technology. Now that empires ruled people in faraway places, new social hierarchies developed as rulers sought methods to hold their diverse empires together.

Even after the Iron Age, iron smelting technologies continued to reshape relationships between people. The huge empires of Rome and Han China depended on iron tools as their agricultural efforts spread rapidly to new areas. Once again, more food meant that empires could support more people, now in densely populated cities. To manage their large empires, rulers built new roads and infrastructure.³

As for the lower classes, iron technology meant that even peasant farmers could afford tools. According to historian Daniel Headrick, “for most people, it was iron, not bronze, that brought an end to the Stone Age.”

Gender mattered when it came to iron work. The production of iron was done by men in most regions, with some variations. In places where women dominated farming, as in large parts of Central Africa, it was probably women who drove the adoption of iron. Even here, however, most metal-workers were men. As iron became more important to communities, men often held more power in those communities.

One Metal, Many Paths

The journey to iron technology took different routes. In Bantu Africa, the route included termite mounds and complex gender relationships. Historians Catherine Fourshey, Rhonda Gonzales, and Christine Saidi explain how the massive termite mounds of Central Africa helped inspire iron kilns. Bantu iron smelters could repurpose a termite hill as the foundation for a new kiln and then use clay from the same mound to build furnace walls.

When it came to metal working, Bantu society did not strictly separate “men’s work” from “women’s work.” It was far more complex. Evidence from the Bantu language confirms that Bantu speakers made connections linking termite mounds, iron smelting, and motherhood. The iron kilns were associated with the idea of giving birth, though it was men who worked them. In this way “the male production of iron” was linked to matrilineal history through “the metaphor of birth or female reproduction.” Matrilineal societies trace ancestry through mothers. This is just one example of the variety of relationships linking humans to iron working, their environment, and each other.

1 Smelting is the process of extracting metal from ore by melting it. Ore is a kind of rock that has a lot of metal in it.
2 Bantu refers to a group of languages spoken in Central and Southern Africa.
3 Infrastructure refers to the physical and organizational structures that allow a society to function. It can refer to physical structures like bridges, roads, and water supply, but it can also refer to organizational structures like the education system.