A long, long time ago, the earth was ruled by a race of pig-zombie people called zombie pigmen. These creatures were vicious and mean and cruel and wanted nothing more than to rule the world. They had originally came to be by a human touching a pig and getting struck by lightning.
It was mindlessly wandering the world, and eventually found some others. They got together and went underground in search of a material suitable for a weapon. They found gold. They were only able to be killed by gold swords, so they decided that no human should get one. After they got golden swords, they got an insane idea; they were going to enslave the human race.
They destroyed the humans one village at a time, until they conquered the entire world. Then, they forced the humans to build them a fortress. They worked long and hard to build this seemingly impossible fortress for the pigmen.
One group of humans, though, wasn't going to stand for this. They figured out the one weakness of the pigmen; gold. They decided that in one week's time, they would break into the pigman armory and steal the golden swords.
After one week, their plan got going. They managed to steal 3 swords per night for 15 days. Then, they rebelled. But, they were careful to avoid the majority of the pigmen. Instead, they went straight for the king.
That night, the humans sneaked into the king's chamber of the fortress. At the time, it was night, and the king was in bed, with guards at his door. So, the humans were able to find some spiders to ride up the walls to his bedroom window. After they made sure that there were no guards in his room, the humans went in.
As the humans approached up to the king's bed, he began to stir. They were too loud, and woke him up. He reached for his sword, but it was too late; teh humans had already run him through with a golden sword. Then, the human who stabbed him pulled out the sword and took his head off. The king was dead and the humans were free.
After the humans got out, they went and made a portal to the Nether, a fiery, hell-like place covered in fire and lava. This is where they banished the zombie pigmen and their fortress. Then, they broke the portal, which sealed the zombie pigmen in forever. Now, anyone brave (or foolish) enough can go to the nether, where the last few zombie pigmen live in the ruins of their fortress. But, as the last pigman was forced in, he made a statement; "On this day in one thousand years, the Nether will burst through the surface, and when we return, we will take revenge for what you have done to us." At the time, they dismissed it as nothing. It has been 999 years and eleven months since then, and it is now growing warmer by the day. We are preparing now for the imminent attack. The zombie pigmen will return.