Hanuman was just one of such 4 monkeys. This monkey group was instrumental in giving Rama key information regarding Sita. They served him build a bridge across the seas, and cross over having a monkey Military that productively stormed the demon stronghold and freed Sita. Lord Śiva reported to him: https://worldfamousvashikaranspec69246.wikibyby.com/1795936/the_fact_about_mohini_that_no_one_is_suggesting