The Named and Unnamed 4:164
There are messengers that Allah narrated their stories to you from before and messengers He did not narrate their stories to you. And Allah spoke to Moses without a medium.
It is reported that Allah have sent several thousand messengers, some named and most unnamed, with the named ones being mentioned in scripture.
Even though we do not know who the unnamed are, we should be thankful to Allah for those great thinkers of the past, some who are called philosophers or reformers. They saw the unfavorable conditions of their people, and reflected upon their problems. They sincerely turned their hearts to their Creator, and used their intellect to reflect upon the scriptures, the messengers and the signs in creation for solutions.
Allah is always in charge and He grants guidance and wisdom to whomever He pleases, whenever He pleases, named and unnamed.