You Do Need power plug adapter while traveling from Mauritania to Peru.

Here is Why You Need An Adapter

The outlet and plug type used in Peru are A, B and C and in Mauritania is C. This is how they look like.

Mauritania

In Mauritania, outlets of type C are in use.

Type C

Peru

In Peru, outlets of type A, B and C are in use.

Type A

Type B

Type C