What do you call the Minecraft event that you can't enter certain regions stop something like the GommeHD.net stage

What do you call the Minecraft event that you can't enter certain regions stop something like the GommeHD.net stage Thank you?

There's no event for that. You can either put Barrier blocks or code something (do you want to do that?)

Then you have to check the position of the player and compare it with the barrier.

Player Move Event

Then query where the players are located, if prohibited simply event.setCancelled (true);

It is best to teleport the player to himself

So usually something like that is done with so-called barrier blocks. These are invisible, indestructible in survival mode blocks. You can get them in creative mode with the command / give @p minecraft: barrier