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 ("Master Sun"), is composed of 13 chapters. Each one is devoted to a different set of skills or art 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 Shenzong of Song in 1080. The Art of War remains one of the most influential works on strategy of all time and has shaped both East Asian and Western military theory and thinking. The book contains a detailed explanation and analysis of the 5th-century BC Chinese military, from weapons, environmental conditions, and strategy to rank and discipline. Sun also stressed the importance of intelligence operatives and espionage to the war effort. Considered one of history's finest military tacticians and analysts, his teachings and strategies formed the basis of advanced military training throughout the world.