Throughout your life, your communities and networks have expanded. When you were a baby, your life included just a few people—maybe parents or siblings, or a grandparent, or other caretakers. When you went to kindergarten, you probably only knew the kids in your class or those in your neighborhood. But as you grew older, you began to create your own networks with people farther away—maybe some you only knew through social media, people who liked the same music or played the same games as you. Your sense of community also grew over time, extending from your neighborhood to those who lived in other parts of town or even other cities or countries. But your networks and communities don’t always expand. Sometimes, they can shrink: Maybe you lost interest in some online forum or lost touch with people you don’t see very often.

Throughout human history, we can see these same basic patterns in our species. Our foraging ancestors lived in family groups, and probably thought of their community as a group of less than 250 people. We think this is true because there’s some evidence that suggests that’s how large a group can get without laws or writing. These family groups met and traded with their neighbors. While networks grew as specific trade goods or resource moved a long distance, community sizes stayed the same. The growth of the city and the state changed all those things, at least a bit. The city could be a community of thousands—even tens of thousands—of people who often lived under the control of a government that set laws and developed social hierarchies that dictated how people acted towards each other. Cities and states both facilitated trade, first in very local networks, and then along much longer distances, although this trade probably remained limited to a few high-value luxury or durable goods.

In this unit, we look at how very large states—which are called empires—and portable belief systems began to develop and spread. Both empires and portable belief systems represented another scale of growth for communities and networks, at least for some people. Let’s talk about how and why that happened. Before we do, however, I want to remind you: just like the shift from foraging to farming, the growth of communities and networks didn’t happen for everyone at the same time or at the same rate in every place. And sometimes, even if just temporarily, they shrank. Still, the overall trend in this period was of growth, so let’s discuss how that expansion happened.

The development of portable belief systems

First, let’s talk about portable belief systems—what we often simply call religions.

Not everyone in the world today is religious, but our world still contains vast communities of people who share faiths—Hinduism, Buddhism, Christianity, Judaism, Islam, Jainism, Sikhism, Bahai, among many others. While some belief systems are very local, the ones I just named stretch across continents and contain millions of adherents. Within those communities there may be disagreements and differences, but they are still each bound together by a set of common beliefs and practices and by fundamental understandings about ways one should act in the world.

Religions develop when people try to answer the big questions about life and the world. Why are we here? How did we get here? How does this all work? As people shared these ideas in different places and times, they often identified a set of people—priests and priestesses or shamans, for example—who specialized in answering these questions. As states emerged, these specialists were often involved in government or in the distribution of resources.

Most belief systems early in this era were tied to a location or a group of people. People understood their gods or spirits as tied to sites like rivers and mountains, or they resided in a single shrine or temple. But starting about 3,000 years ago, some people began to think of their gods as universal—able to spread across the whole world. The idea is that communication with those gods (or God) happened no matter where believers were, and everyone, regardless of location, could become part of their religious community. These beliefs in universal gods allowed people to create vast networks based on religion. It meant that even if they traveled for trade or other reasons, they might find a like-minded member of their religion to do business with or to reside or worship with. There were huge advantages to joining these universal, portable religions, and many people did so—although of course some did not!

But it’s important to note that as religions spread and became larger, people adapted them to fit their local contexts. For example, when a community adopted a belief system that originated in a different region, they made changes to it so it made sense to them. Sometimes people even mixed the new religion with their older, local beliefs. As we’ll see in this unit, the expansion of religions meant a lot of mixing, matching, and adapting—a process called syncretism. It’s worth learning about this kind of merging and changing because it happens so often in human history, and not just with religion.

The growth of empires

As religions grew, so did the state. Remember, states are political units. They are communities that share a single ruler (or system of rulers) and a unified set of laws, borders, and government institutions. States also grow, often by conquering new groups of people who have different laws and government. And as states expanded, they faced a problem: how to make conquered people follow their rules and government.

One answer to this question was the empire. Empires are large states, but they’re more than that. Empires are a solution to ruling a society that contains many different communities—people in different cities and regions with diverse religions, ethnicities, and languages. Generally, the empire solution to this problem isn’t to make everyone equal. Rather, in an empire, one group of people has quite a bit of power over the others, who are treated as inferior.

There have been lots of different types of empires since the first empire was established in Mesopotamia by Sargon of Akkad in about 2400 BCE. In many cases, the rulers of an empire let the various people they ruled live out their lives with their own customs and practices pretty much intact, so long as the conquered people paid a tribute or taxes. In other cases, empires were very oppressive, ruthlessly exploiting the people they colonized to enrich their ruling class. And not all large states became empires. For most of Egypt’s history during this period, for example, it was a very large and powerful state that had multiple regions but thought of them all as part of the Egyptian state.

Empires, which were created in different places and times, were a useful solution to the problem of ruling over large and diverse communities. In addition to Sargon of Akkad’s empire in Mesopotamia, there were others: the vast Persian Empire of Xerxes and Darius, the Zhou and Qin dynasties in China, the Mauryan and Gupta empires in South Asia, and the Macedonian Empire of Alexander the Great.

Two of the great empires of the ancient Afro-Eurasian world were the Roman Empire and Han Dynasty China. These were both impressive imperial states because they were vast and developed new technologies to rule over great distances, with innovations such as sophisticated road systems and government bureaucracies. They also both lasted a long time, managing to successfully deal with the diversity and size of the populations they controlled.

Importantly, both states existed around the same time, which meant that they also helped create a huge network of trade that extended from one side of Afro-Eurasia (Britain) to the other (China and Japan). However, they differed from each other in many ways, including how they viewed the role of women in their imperial societies.

Conclusion

Eventually, both vast states collapsed. Empires often became politically unstable. This was partly because some populations within them were not treated as well as others. The fact that the Roman Empire and Han Dynasty China survived as long as they did is a testament to the systems they developed to hold everything together. But just as sometimes happens with people’s personal communities and networks, imperial communities and networks sometimes shrink. That’s a theme we will explore in the next unit, where we look at the regional webs that followed the collapse of the great world empires.