I personally think you could pull this off even as early as the Bronze age if you are dedicated enough to it. Granted it will make the whole process less centralized and efficient, but you didn't make that one of the requirements.

What's to prevent for example the Assyrian king from setting up a Stasi like system? What does he need? A bureacracy capable of handling the information? I think it's possible.

There was less literacy in those times, but there are also factors that allow that to be a non-issue. For example the spies don't have to be literate, only the people penning down and processing the information have to be. The area to be monitored is also smaller since most people live in or close to cities.

All the Assyrian king has to do is set up a spy system in every city with a loyal guy in charge. It's of course less efficient, but there are also factors that make it harder to revolt in ancient times.

I personally think you could pull this off even as early as the Bronze age if you are dedicated enough to it. Granted it will make the whole process less centralized and efficient, but you didn't make that one of the requirements.

What's to prevent for example the Assyrian king from setting up a Stasi like system? What does he need? A bureaucracy capable of handling the information? I think it's possible.

There was less literacy in those times, but there are also factors that allow that to be a non-issue. For example the spies don't have to be literate, only the people penning down and processing the information have to be. The area to be monitored is also smaller since most people live in or close to cities.

All the Assyrian king has to do is set up a spy system in every city with a loyal guy in charge. It's of course less efficient, but there are also factors that make it harder to revolt in ancient times.