Short answers, pulled from the story.
Sun Tzu was a Chinese military general, strategist, philosopher, and writer traditionally dated to 544-496 BC and credited as the author of The Art of War. The Han dynasty historian Sima Qian placed him as a minister to King Helü of Wu, though his historical existence is uncertain.
Sun Tzu's historical existence is uncertain. Beginning in the 12th century, Song dynasty scholars such as Ye Shi noted that the Zuo Zhuan, a detailed record of the period, never mentions him at all, and some think his name may have been an invented title meaning the fugitive warrior.
The Art of War is a Classical Chinese text from the Warring States period made up of 13 chapters covering military strategy and tactics. It also advocates diplomacy and cultivating relationships with other states, and incorporates Taoist rhetoric that favors silence and avoiding confrontation.
Bamboo slips containing an early version of The Art of War were unearthed by construction workers at Yinque Shan in Shandong in 1972. The cache had been sealed sometime between 134 and 118 BC and also contained Sun Bin's long lost Military Methods.
The Art of War reached Nara Japan in the year 760 and quickly became popular among Japanese generals. It later influenced the Sengoku period unifiers Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu, and Admiral Tōgō Heihachirō read it before leading Japan's navy to victory in the Russo-Japanese War.
Mao Zedong partly credited his 1949 victory over Chiang Kai-shek to lessons from The Art of War, and its influence shows up in his own Little Red Book. Vietnamese general Võ Nguyên Giáp studied it closely after Ho Chi Minh had it translated, and American generals Douglas MacArthur and Norman Schwarzkopf Jr. are also cited as having drawn on the book.