Lighting - How did they achieve this lighting?

Hello all of you fantastic CG experts!  I had a question regarding the lighting in this screenshot.  For the scene I am making I wanted the lighting to be a lot like this.

The main question I had was about the lighting in the bottom right corner of the image.  How did they get the light to be really strong on top of the wall and have a smooth transition so that the light on the bottom of the wall is really dim, yet also having the floor lit up?

Anybody who could help with this will officially be my favourite person!

Even if you are just passing by and don't know how to help, I hope that you have a fantastic rest of your day!