The first-ever "Muslim" historian was "Imam" Jareer bin Rustam al-Tabari who died about 300 years after the exalted Prophet Muhammad. In fact, he was a Zoroastrian from Tabaristan, Persia.
He lived during the Abbasid dynasty and served the political purposes of the emperors.
IMAM TABARI'S STRANGE CONFESSION: [838-923 CE, 224-310 AH, Abu Ja'far Muhammad ibn Jareer / ibn Rustam at-Tabari]
“I am writing this book as I hear from the narrators. If anything sounds absurd, I should not be blamed or held accountable. The responsibility of all errors or blunders rests squarely on the shoulders of those who have narrated these stories to me.” So, Tabari wrote nothing but hearsay.
Tabari's Tareekhil Umam Wal Mulook (The History of Nations and Kings) popularly called "Mother of All Histories" is the first-ever "History of Islam" written by 'Imam' Tabari at the junction of the third and fourth century AH. He died in 310 AH, 3 centuries after the Prophet (S). What were his sources? Not a scrap of paper! "He told me this who heard it from him who heard it from so and so," and so on. By compiling his 13 volume History and his 30 volume Exposition of the Qur’an under royal patronage, he became the Super Imam. The later historians until this day have persisted in following the trails of the Super Imam.