Mountains play a very important role in geology, and earth geography.

Mountains play a very important role in geology, and earth geography.
Mountains, can create deserts and jungles.
Also, there are some mountains that are very famous, like Everest, and Kilimanjaro.
In many wars, mountains have played a decisive role in the result of the war.
Crossing a mountain for a big army, is not as easy as we think.

Hello alirakiyan

I think, the text will sound much better if reformulated as follows:

Mountains are very important to the sciences of geography and geography.
Mountains contribute to the creation of deserts and jungles.
Many mountains are well-known throughout the world, such as Everest and Kilimanjaro.
During the time of war, mountains often end up playing a decisive role.
For an army it always represents much challenge trying to cross a mountainous terrain.

Other than that, the contained sentences are easy to understand, for which you deserve a credit. You could you use listening to some news in English to get a better 'feeling' of the language. Regards.

Thank you Larsen.