"Repeating Regions(?)" Glitch

I first downloaded Minecraft and created a creative world. I came over to a spot to start building, but then I looked over to the right and found that the section of the world had been repeating an image of the worlds regions. I can't really explain it that well, since I have no idea what to say about it, but it's sort of in a wall form, and you can go through the "wall."