Does the fact that the Prophet Muhammad, peace and blessings be upon him, was not mentioned in history books until 50-100 years after his death, that the first biography of him was written 100 years after his death, and that the first Mus'haf was written in 652 CE, cast doubt on his existence?

Attempts to cast doubt on the existence of the Prophet Muhammad, peace and blessings be upon him, are sophistry and stubborn denial of truth. His existence is established by continuous transmission (tawatur), and his states, sayings, and actions have been transmitted with extreme precision, unmatched by any other historical figure. Muslims have distinguished themselves with robust scientific controls in transmitting and critiquing news, such as the science of Hadith (definition) and al-Jarh wa al-Ta'dil (discrediting and accrediting narrators).

Moreover, the Holy Quran, which has been preserved from alteration, was written during the Prophet's lifetime, peace and blessings be upon him, and transmitted by Muslims generation after generation. It mentions the Prophet, peace and blessings be upon him, his biography, and his law, in addition to the prophecies about him in the sacred scriptures. As for the claim that the first copy of the Quran was written twenty years after the Prophet's death, peace and blessings be upon him, it is a grave error. The Quran was written during his lifetime and compiled during the eras of Abu Bakr and Uthman, may Allah be pleased with them both. The preserved copies of ancient Quranic manuscripts date back to the early Hijri centuries.