Introduction

Hello friend!
If you've read the world description and are wondering what on earth you have found here, I have a little quickstart guide for you that will give you the most important infos in a nutshell. I'll link relevant articles for additional info in the text and at the bottom of the article, so you can go and venture further if you find yourself intrigued.
I won't start off with a long lecture of historical events that led to the state the world of the Hummelverse is in - you can check out a list of the significant history further down on this page if that's your thing. Instead, let's talk about the basics and make our way to understanding what on Earth is going on in this Hummelverse from there.

So about those talking tanks ...

Yep, they're a thing. Tanks are the "ruling species" in this setting.

When you think about talking vehicles, you're probably thinking Disney's Cars, or Thomas the Tank Engine. But what you're looking at is more like low-tech Transformers without the transforming and without the alien part.
Tanks, planes, ships, some other vehicles, and even factories are sentient in the Hummelverse. Their sentience is driven by AI cores, basically "computer brains" that were invented by humans - before they went extinct.

Wait, humans? Extinct? Explain.

You read that right. The humans are gone.

Why? They died. All of them. Or at least all we know about. It's been 100 years since the first apocalypse, and all that's left of the humans by now is their old cities - now crumbling - and some of their culture and technology that lived on inside the machines' minds. The Earth at large has become a feral wilderness, roamed by animals and the AIs that the humans left behind after World War III.
New machines are built by the autonomous factories, of which no one knows how they operate or what their agenda is. Rumor has it that there used to be a way to "talk" to them and command them, but would someone claim to be able to, they'd be called a liar and madman.

The first apocalypse ...?

There were two.

The first apocalypse happened during the Cold War, in 1983. When the humans were still around. A maneuver escalated and nuclear bombs were launched. They blew up vital locations in the US and the Soviet Union. What followed was a mass extinction caused by war, famine, diseases, ... you name it.
The war machines fought on even when their human masters died. After all, that's what they were programmed to do! They fought for about twenty years. In that time, new nations and leaders emerged. Unfortunately, they had learned nothing and caused a second apocalypse by digging up some old nuclear bombs that the humans left behind and using them against each other.
Now, with all that destruction, everyone panicked for real. They looted what they could get, turned against each other, killed their former comrades and leaders. The nations fell apart for good.

And now it's all a wasteland...

Not at all, actually.

Earth has recovered really well from the atomic wars, in fact being more green now than it was before, probably. The no-man's-land is the home of the free teams - groups of vehicles that travel and fight together or hold small settlements. Then there's also clans, who hold territories and trade with or fight against each other. They own most of the infrastructure, ensuring the production of fuel and parts that the vehicles need to survive.

But they're ... tanks. How do they do anything except shoot?

I'm glad you ask. The answer is:

I'm serious. Machines in this setting have arms. They kinda look like tow cables with claws at the end. The average tank possesses four of them, and they can be used to lift or manipulate objects. (Or for fist fights.) Apart from that, the machines also have voiceboxes for talking - they can freely choose what their voice sounds like. Radios are used for long-distance or silent communication.
They don't really have eyes in the sense of those cartoon eyes you see on living machine art, or those badass Livastian robot eyes. They use their optical devices like viewports to see, which gives them a sort-of 360° view of their surroundings when they switch between the devices.
Vehicles consume fuel and other supplies like water, electricity, and oil like the ones in our world do.

Where are you going? You promised history.

Right ... Let's do this.

In the Hummelverse, computers were developed much sooner. This led to the creation of the AI. A quick timeline of the events from the point of divergence (before which everything happened the same as on the real version of Earth), up to the first apocalypse:

1851: Charles Babbage presents a working prototype of his analytical engine.

1899: Nikola Tesla invents the first computer.

1939: Zuse and Aike develop Tesla's ideas further and invent a much smaller version of Tesla's computers.

1941: During the second World War, artificial intelligence is used for warfare for the first time.

1946: Germany loses the (elongated) war and is divided.

1947: Russia takes interest in the AI technology and an arms race begins.

1983: The Cold War escalates and atomic bombs devastate Europe and America.

Recommended Reading

These articles contain more elaborate explanations on the things mentioned here, among other basic info.