What part of the 6 patriarchs is not myth and rumor?
Also, the bit about the 5th P, what I said above was "There is also a rumor that the 5th patriarch was a Taoist in his previous life." in case you would like to slander me on the points I actually did say instead of the one's you like to pretend I said.
For that one, check out:
http://ctzen.org/sunnyvale/enUS/index.php?option=com_content&task=view&id=39&Itemid=59
The Fifth Patriarch HongRen (601-674) was a Taoist in his previous life, and planted pine trees on Twin Peaks Mountain. He met Daoxin and asked about the Way. Daoxin said, “You’re too old. Even if I explain it to you, can you spread it widely? Come again [in the next life] and I’ll be waiting for you.”
The old Taoist left and met a girl washing clothes by the river. He asked her, “May I stay over at your place?” The girl said, “My father and brothers are at home. You should ask them.” The old man said, “If you grant me consent, then I will.” She consented and the old man turned back and left.
Some time later the girl was found to be pregnant. Her father was furious and drove her out of the house. She made a living by making garments and passed the nights under others’ roofs. When she gave birth to a son, she feared he was a bad omen and left the baby in a sullied ditch. The next morning, she found the baby further upstream, bright and unblemished. Shocked, she kept and raised the child. Mother and son begged for food. The neighbors called him, “No-Name Child,” because he had no father.
Lest you get too carried away with all this, keep in mind that the The Princeton Dictionary of Buddhism page 265 claims that the first mention of the 4th P Daoxin being tied to the 1st 3 patriarchs is not found until the 713 CE mention in the Chuan Fabio Ji (Annals of the transmission of the dharma jewel), which again is during the period of the patriarchs.
This to me confirms that the East Mountain teachings are fairly murky, yet still very likely; however, the first three patriarchs are, as you said of Bodhidharma, even more "cloud hidden".