Чжурчжэни
In the 12th century, China's first permanent standing navy was established by the Southern Song dynasty, the headquarters of the Admiralty stationed at Dinghai. This came about after the conquest of northern China by the Jurchen people (see Jin dynasty) in 1127, while the Song imperial court fled south from Kaifeng to Hangzhou. Equipped with the magnetic compass and knowledge of Shen Kuo's famous treatise (on the concept of true north), the Chinese became proficient experts of navigation in their day. They raised their naval strength from a mere 11 squadrons of 3,000 marines to 20 squadrons of 52,000 marines in a century's time.