The Song dynasty is divided into two distinct periods: Northern Song and Southern Song. During the Northern Song (; 960–1127), the Song capital was in the northern city of Bianjing (now Kaifeng) and the dynasty controlled most of what is now Eastern China. The Southern Song (; 1127–1279) refers to the period after the Song lost control of its northern half to the Jurchen-led Jin dynasty in the Jin–Song Wars. During this time, the Song court retreated south of the Yangtze and established its capital at Lin'an (now Hangzhou). Although the Song dynasty had lost control of the traditional "birthplace of Chinese civilization" along the Yellow River, the Song economy was still strong, as the Southern Song empire contained a large population and productive agricultural land. The Southern Song dynasty considerably bolstered its naval strength to defend its waters and land borders and to conduct maritime missions abroad. To repel the Jin, and later the Mongols, the Song developed revolutionary new military technology augmented by the use of gunpowder.