No, a group of mountain slopes in one area is not typically called a "system." Here's why:

* System usually implies a network of interconnected parts working together for a specific purpose. This doesn't apply to mountain slopes.

* Mountain ranges are the most common term for a group of mountains in one area.

* Mountain chains are another term for a series of connected mountains, often formed by the same geological process.

While "system" might be used in a more technical or scientific context, it's not the standard terminology for describing a collection of mountain slopes.