Hanuman was just one of these 4 monkeys. This monkey group was instrumental in giving Rama critical specifics of Sita. They aided him make a bridge across the seas, and cross in excess of using a monkey Military that effectively stormed the demon stronghold and freed Sita. भस्मसादभवदैत्यो दुष्टचेष्टितमन्तकृत् ॥ https://remingtonawsng.wikissl.com/1778551/everything_about_krishna