The Writings of Homer
As mentioned earlier, the Mycenaean civilization had used script mainly for accounting purposes. However, during the Dorian invasion there was no script at all, which is why not very much is known about this period.
** The image above shows "Homer Singing with his Lyre" by Felix Boisselier
By Attributed to Felix Boisselier (1776-1811) [Public domain], via Wikimedia Commons
Most of our knowledge is from excavations and from text which was written in a later period than the Dorian invasion itself. One of the people who wrote about these times was Homer.
Though not much is known about him, it is known that he did write the oldest book in Europe, the Illiad and Odyssey, which has been read by many since it was first written in the 9th or 8th century B.C.
There is some doubt to the accuracy of the writings of Homer as many of his stories were passed down through generations and obviously, certain elements may have been twisted or changed.
However, as there is no alternative to his writings for this period we have no choice. It is important to remember though that his writings were in the form of literature and not of recorded history.