Just to be clear, what exactly don't you believe about the generally accepted history of early Islam?
The quotes I posted give a good overview of the problems and why many people unfamiliar with contemporary scholarship mistake theology for history.
Yes
Did he start in Mecca and then go to Yathri
Probably, but can't be certain
The Quran certainly doesn't appear to have emerged in a pagan backwater though, so the Mecca of Islamic tradition is not likely to be accurate.
Did he oversee the slaughter of the Banu Quraiza?
Maybe, maybe not.
No evidence outside of theological writings from centuries after the fact that contain numerous clear and obvious fabrications.
A bit like the Gospels or Acts of the Apostles (except the Biblical texts were written down much closer to actual events).
Much of the sirah and hadith literature very much seems to have been written to explain difficult or debated passages of the Quran.
Why do you put so much faith in these "historical" texts that contains so many clear and obvious fabrications and were written by people with clear religious agendas in an era when history was almost always a self-serving exercise without a goal of factual accuracy and objectivity?