Prevent Minecraft Monster spawning?

I want to prevent monsters from spawning in a certain area in my Minecraft world (1.15.2). Unfortunately, this area can't be illuminated. Overall, the difficulty has to stay on easy, because I need monsters in another part of the world. My question: is there a command that prevents spawning of monsters within a radius of x blocks? Or another solution?

I believe that you can place slaps in this area so there shouldn't be any mobs of chips, but why can't you illuminate?

Unfortunately this only works with Spigot / Bukkit plugins such as WorldGuard: https://worldguard.enginehub.org/en/latest/regions/flags/

The flag is "mob-spawning". So first define a region and then set the flag "mob-spawning" to false in the region

Otherwise just use other vanilla methods, most of which can be found on the Minecraft Wiki

So I'm currently building an "ecosystem" completely under glass with the upper world, water and nothing. The nether is underground and there's actually a lot of lava there, but zombies spawn on the open spaces. And it doesn't look so cool when there are torches everywhere

That sounds good. Are there tutorials on YouTube or something? I'm not really familiar with mods and plugins

Here's one in English:

But be careful: He also installed WorldEdit as a plugin (which I highly recommend). That is why he can use the wooden ax to mark regions interactively (e.g. With // wall - yes 2 slashes! - and then right-click and left-click with the ax)

Do you use carpets in your ecosystem? No right? Sunburst you could do glowdtone under the carpets and then it will shine

Thank you for the quick and good answer. I do it exactly as described 👌

You can always kill all entities except the player in the area with a command block. Do you know how to do it

Easy

/ kill @e

XD

Do not do that

/ kill @e [type =! Player, distance = .Radius]

is the right command