Simple:
* The hikers followed the winding path through the chain of hills.
* A chain of hills formed a natural barrier between the two valleys.
* The sun dipped behind the chain of hills, casting long shadows across the landscape.
More descriptive:
* The chain of hills, a low, rolling expanse, stretched as far as the eye could see.
* The setting sun painted the chain of hills in vibrant hues of orange and pink.
* We drove through a chain of hills that was dotted with wildflowers and ancient ruins.
Figurative:
* His life was a chain of hills, each peak representing a new challenge and each valley a moment of rest.
* The chain of hills seemed to rise up from the earth like a dragon's spine.
Remember: You can adjust the sentence structure and word choice to fit your writing style and the context of your writing.