The Battle of Qatwan is fought in September 1141 between the Kara-Khitan Khanate and the Seljuq Empire and its vassal-state the Kara-Khanids.
The Seljuqs are decisively defeated, which signals the beginning of the end of the Great Seljuk Empire.
"The Master said, 'A true teacher is one who, keeping the past alive, is also able to understand the present.'"
― Confucius, Analects, Book 2, Chapter 11