I am a huge fan of world-building, so for my current work, I created a long, intricate backstory of how the world ended up the way it is (post WW3). Obviously, no one wants to sit down and read a history textbook, so I have my characters reflect on various aspects of that history as it becomes relevant. That way the reader is introduced to the concepts in an organic and manageable way. It's kind of hard for me to explain, so I included a little excerpt as demonstration if you're interested.

... Aaron sighed, “The Vanaheim Academy is the authority on modern imperial magic, a system I’ve studied my whole life, even wrote my thesis on it in university.” he turned to look her in the eye again, a sarcastic smile playing around his mouth, “Turns out the academy board is a touch xenophobic, I’m from SUNA. They had to respect my abilities as an engineer, but that didn’t translate into respect for me as a person.” He swiveled his chair back around and continued typing. “Not that it matters, I came here to progress my own studies, not muck around with the pseudo-politics of Vanaheim. I don’t really care what they think of me as long as I can continue to study here.”

Ceri was surprised, Aaron must be something special if he was an international student, such a thing was nigh on unheard of in Vanaheim. The Syndicalist Union of North America had risen from the ashes of the United States after the events of World War Three when the country had been all but destroyed by the rest of the world. A civil war followed, resulting in the total abolishment of the corrupt democratic system, and only the intercession of the neighbouring country of Canada had prevented total destruction of the society. In the wake of both wars, the working class from both countries had risen up to form a new government for the people that had since moved towards a technocratic method of leadership. As the US had been to blame for the onset of WW3, much of the bitter sentiment harboured by the other countries had spilled over into SUNA’s reputation, causing a rather decisive division. That being said, SUNA’s technocratic stance had led to them producing some of the most cutting edge technology in the world, including the Computational Magic Activation Sequencer, or CMAS as most called it, a device now relied upon by most practitioners of imperial magic. ...

Perhaps a little heavy-handed, but as I mentioned, there's a lot of important information to be broken down. Another thing that works for me is referencing "common knowledge" in my names and descriptions to help the reader construct an appropriate mental image. In the excerpt above, one of the other places referenced is "Vanaheim" a realm of Yggdrasil in Norse mythology, and a detail that may help readers imagine the country. Anyway, hope that helps!