"Mountain terrain" refers to the land and landscape found in mountains. It includes the physical features like steep slopes, rocky surfaces, and high elevations that can be found in mountainous regions. Full definition
It's really exciting to see young women riding big mountain terrain with so much confidence, talent and flair! (skifernie.com)
The drive will show you through gorgeous mountain terrain where you can observe local culture in a jungle - like setting. (komodotravellers.com)
The explanation for why this is the case seems to lie with the uneven terrain and shallow waters common to streams in steep mountain terrain. (sciencedaily.com)