About Sun Tzu
If you are talking to a western person about Sun Tzu the most common pronunciation is "Sun Sue" like the Sun in the sky plus a boy named Sue. This is nothing like the correct Chinese pronunciation which is "Sun Tzzz" Sun rhymes with un in the German word "unter" or the Spanish-English word (Military) "junta" plus Tzzz like the last sound you make when you say "words".
The legend goes that Sun Tzu was born into minor nobility in what is now Shandong, a part of China north of Shanghai that became famous for Confucius and the really tasty Shandong Chicken. Born "Sun Wu", he was given a good education and like Machiavelli, he wrote a military treatise in order to get noticed and hired by royalty. Unlike Machiavelli, it worked.
Sun Wu expanded his 13 chapter Art of War into 82 chapters and trained the army. Eventually he broke the peace by invading the southern state of Yue. Other conflicts ensured but although his troops were once outnumbered 30,000 to 200,000 he was always victorious. Many successes followed and continued after his death. Some considered his death to be another of his deceptions.
Finally though, the kingdom was defeated several years after his reported death. Just over 100 years later his descendant, Sun Bing, lead troops to victory again and wrote his own treatise. Sun Wu's name was changed to Sun Tzu on the Art of War as a sign of his status a master of philosophy. The "Tzu - " is similarly shared with Lao Tzu - , and Confucius (whose Chinese name is Kon Tzu - ).
The place and time of the creation of the Art of War are quite certain and supported by numerous historical records and evidences. On the other hand there is no information on Sun Tzu that isn't contradicted by other sources.
If there was a single person behind the Art of War, we can assume that they would have wanted to remain in safe obscurity as recommended in the book itself. This may be further evidence of the brilliance of its writer.
There are several instances in Asian history of people that created fake personas complete with homes, families and documents so that they could carry on their government or military work without showing the enemy their true identities. This made them invulnerable to attack.
Probably some parts of the legend are true, but at this late stage there is no way to tell which parts.