Throughout your life, your communities and networks have evolved. When you were a baby, your life included just a few people—maybe parents or siblings, a grandparent, or other caretakers. In kindergarten, you probably only knew the kids in your class or kids 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 grew over time to include those who lived in other parts of town or even other cities or countries. But networks and communities don’t always expand. Sometimes, they can shrink. Maybe you lost interest in some online game or lost touch with people you don’t see very often or moved houses.

Throughout human history, our species has followed these same basic patterns. Our foraging ancestors lived in family groups and likely thought of their community as a group of fewer than 250 people. We think this is true because evidence 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 resources moved long distances, community sizes stayed the same. The growth of the city and the state changed all those things, at least a bit. A city could be a community of thousands—even tens of thousands—of people who often lived under the control of a government. The government set laws and developed social systems that dictated how people behaved. Cities and states both supported trade, first in very local networks and then along much longer distances, although this trade probably remained limited to a few high-value goods.

In this unit, we look at how very large states—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. But first, keep in mind that 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, these networks shrank. Still, this period saw an overall trend 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. They include Hinduism, Buddhism, Christianity, Judaism, Islam, Jainism, Sikhism and Bahai, among many others. While some belief systems are very local, the religions just mentioned stretch across continents and contain millions of followers. Those communities each have their own disagreements and differences. But they are still bound together by a set of common beliefs and practices and by fundamental understandings about ways one should act in the world.

Most belief systems early in this era were tied to a location or a group of people. People understood their gods or spirits as attached 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 world. They believed people could communicate with their gods (or god) no matter where they were. 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, they might find a like-minded member of their religion to do business with or to live 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 grew, people adapted them to fit their local contexts. For example, when a community adopted a belief system that came from a different region, they changed it so it made sense to them. Sometimes people even mixed the new religion with their 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. This kind of merging and changing 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, or more explicitly they are communities that share a single ruler (or system of rulers) and a unified set of laws, borders, and government institutions. States grow, often by conquering new groups of people who have different laws and governments. As states expanded, they faced a problem with 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 many 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.

The first empire was established in Mesopotamia (modern-day Iraq) by Sargon of Akkad around 2400 BCE. Since then, there have been different types of empires. In many cases, the rulers of an empire let their subjects carry on their own customs and practices, as long as the conquered people paid tribute or taxes. In other cases, empires were very oppressive, taking advantage of the people they colonized to enrich their ruling class.

Empires were useful solutions to the problem of ruling over large and diverse communities. Empires were created in different places and times. In addition to Sargon of Akkad’s empire in Mesopotamia, there was 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 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 large and developed new technologies to rule over great distances. These included innovations such as sophisticated road systems and government bureaucracies, made up of many officials and departments. Both empires also lasted a long time, successfully managing to deal with the diversity and size of the populations they controlled.

Importantly, both states existed around the same time. This 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, such as how they viewed the role of women in their imperial societies.

Conclusion

Eventually, both large states collapsed. Empires often became politically unstable, 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 due 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 effects following the collapse of these great world empires.