When was the Prophetic Biography (Sira) compiled, and is everything mentioned in it authentic?

Among the first to compile the Siyar (biographies) were Musa ibn Uqbah, then Sulayman ibn Tarkhan, and then Muhammad ibn Ishaq, whose Sirah is considered one of the most comprehensive and on which most people rely. Not everything in the books of Sirah is authentic; rather, some of it is weak or fabricated. A Muslim should pay attention to it, for the Companions used to teach their children the Maghazi (military expeditions) and narrate them to them.