The Art of War is an ancient Chinese military treatise dating from the Late Spring and Autumn Period (roughly 5th century BC). The work, which is attributed to the ancient Chinese military strategist Sun Tzu is composed of 13 chapters. Each one is devoted to a different set of skills related to warfare and how it applies to military strategy and tactics. For almost 1,500 years it was the lead text in an anthology that was formalized as the Seven Military Classics by Emperor Shandong of Song in 1080. The Art of War remains the most influential strategy text in East Asian warfare and has influenced both Eastern and Western military thinking, business tactics, legal strategy, lifestyles and beyond. The book contained a detailed explanation and analysis of the Chinese military, from weapons and strategy to rank and discipline. Sun also stressed the importance of intelligence operatives and espionage to the war effort. Because Sun has long been considered to be one of history's finest military tacticians and analysts, his teachings and strategies formed the basis of advanced military training for millennia to come.