The Shining Path was defined as a terrorist group by the Peruvian government because the group

used cruelty to achieve political goals

Explanation:

The Shining Path was founded in 1970 by the Communist Party of Peru. It was a revolutionary organization that endorsed Maoism. Abimael Guzmán was a leader of Peruvian revolutionary organization Shining Path.

The Shining Path was defined as a terrorist group by the Peruvian government because the group used cruelty to achieve political goals.