making a dark cave

Hi , i am making a level in my game and there is a small cave in it , i am using directional light for the level , but i want to make the cave dark (No lighted) , how could i make that , thanks for your time

I just turned my Ambient Light down, to very dark.
After that, i simply added some light on sticks, in order to simulate the darkness vs. light feeling. You may add as much light as you want (which is probably not as much as in my cave, as i kinda wanted it to be lit.
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