Imagine a question and stream-of-consciousness explanation for which this is the answer: a variety of pre-existing sources , such as conflict stories ( Mark 2 : 1 -- 3 : 6 ) , apocalyptic discourse ( 4 : 1 -- 35 ) , and collections of sayings ( although not the Gospel of Thomas and probably not the Q source )
Question: The Gospel of Mark was written anonymously. Early Christian tradition ascribes it to John Mark, a companion and interpreter of the apostle Peter. Hence its author is often called Mark, even though most modern scholars are doubtful of the Markan tradition and instead regard the author as unknown. It was probably written c. AD 66 -- 70, during Nero's persecution of the Christians in Rome or the Jewish revolt, as suggested by internal references to war in Judea and to persecution. The author used a variety of pre-existing sources, such as conflict stories (Mark 2: 1 -- 3: 6), apocalyptic discourse (4: 1 -- 35), and collections of sayings (although not the Gospel of Thomas and probably not the Q source).

Where did mark get his information to write his gospel?
Stream-of-consciousness: To answer the question, consider the following: The author used a variety of pre-existing sources, such as conflict stories (Mark 2: 1 -- 3: 6), apocalyptic discourse (4: 1 -- 35), and collections of sayings (although not the Gospel of Thomas and probably not the Q source).