Hanuman was one of those 4 monkeys. This monkey team was instrumental in providing Rama key information regarding Sita. They aided him build a bridge over the seas, and cross over by using a monkey Military that effectively stormed the demon stronghold and freed Sita. Lord Śiva stated to him: https://andyhortu.answerblogs.com/37821648/5-easy-facts-about-shabar-mantra-described