Extract the answer to the question from the following context. Question: Why do most scholars agree on the teachings of Gautama Buddha? Context: Pre-sectarian Buddhism is the earliest phase of Buddhism, recognized by nearly all scholars. Its main scriptures are the Vinaya Pitaka and the four principal Nikayas or Agamas. Certain basic teachings appear in many places throughout the early texts, so most scholars conclude that Gautama Buddha must have taught something similar to the Three marks of existence, the Five Aggregates, dependent origination, karma and rebirth, the Four Noble Truths, the Noble Eightfold Path, and nirvana. Some scholars disagree, and have proposed many other theories.
Certain basic teachings appear in many places throughout the early texts