 The earliest mention of "rock oil" (石油), the Chinese name for petroleum, is by a book "Grand Peace Records" from the Northern Song Dynasty, and officially designated the current name by Song Dynasty polymath scientist Shen Kuo using the description found in his famous book "Dream Pool Essays".Due to the chemical characteristics of petroleum that it continues to burn in water, it was widely used by feudal militaries.Some examples include the defense of the city of Jiuquan in Gansu Province in the year 578 against the invading Göktürk army, in which the defenders used petroleum to ignite and destroy the siege engines brought in by the invaders.