In the 21st century, mankind discovered the existence of a new form of energy - Pulse. Study by eminent scientists linked Pulse to many of the things we'd previously considered supernatural, from ESP to the existence of spirits. Yet it was the harnessing of Pulse as a source of energy which brought the most profound changes to society.
Pulse could be transmitted along underground channels across the whole world without loss, and within two generations it was Pulse, not electricity, which powered all the machines and computers, massively more powerful than today's technology thanks to the invention of celestium.
These advances allowed scientists to finally tackle the massive issue of the world's unstable climate, and a device was sunk into the Earth's crust which could save the planet from destruction. Yet the device failed, and made matters much worse instead. For all our technology, mankind struggled in the harsh environment on Earth. A population of seven billion withered to under a billion. Within a short space of time the inevitable happened - a war over the remaining resources. This 'Pulse War' would mark the end of the Timeline family of realms, a watershed moment in history greater than either of the two world wars of the 20th century or any other conflict before.
From Death To Death
Years passed, years of continuous fighting using every weapon in man's arsenal. Chemical, biological nuclear and nanotech weapons added to the destruction wrought by the continuing environmental catastrophe. At the height of the War it was estimated that the Earth's population had dropped to one percent of its pre-war levels... 70 million people, all struggling for survival on a daily basis while still furiously fighting against their enemies.
Finally, a daring plan was put into place, to create four great forcefields to slice the Earth into quarters. Hopefully the isolation would stop the global war until it fizzled out and allowed each quadrant to develop independently. Even if only one set of survivors managed to rebuild society, mankind would have been given another chance.
The plan worked. The war petered out when the Earth was segmented and mankind survived in all four quadrants. But there was a price. The forcefield Barriers leeched the global energy grid of Pulse to keep themselves active, and there was no way to shut them down. Mankind had to relearn all the skills that were forgotten when machines became more competent servants.
The end of the Pulse War is the first year for each of Earth's quadrants and is Year 0 (written Yr0) in the Elements realms.