The traditional Maori world is an oral culture.
Emphasis is on the spoken word, and a person´s mana will raise and fall by the truth of their words. Likewise, the mana of their whanau, hapu and iwi will also raise and fall by the truth of the words of all of the members.
Ko te kai a te rangatira - he korero
The food of the chief is talk
When a chief says something, that is their bond, as their mana (or honour) rests on the truth of their words.
Other cultures, due to the fact that they place emphasis on the written word, often dismiss Maori oral traditions as it was not written down.
One of the main arguments against the reliability of oral traditions is the "Chinese Whisper" theory, which works as follows:
A group of people sit in a circle. The first person whispers a phrase to the person on their side, who in turns whispers to the next person and so forth around the whole circle until it gets back to the original person. There is a very high possibility that the phrase has changed.
Those who argue against the accuracy of oral traditions say that this proves that things change.
However, what these people fail to acknowledge is that oral traditions are not whispered once to a person. It takes years of training and reciting to gain the position of historian. The memory is trained to be able to recall acurately the histories, traditions and genealogies verbatim.