The Alliance Conducted at Sea (海上之盟) was a political alliance in Chinese history between the Song and Jin (金) Dynasties in the early 12th century against the Liao Dynasty. The alliance was negotiated from 1115 to 1123 by envoys who crossed the Bohai Sea. Under the alliance, the two nations agreed to jointly invade the Liao, split captured territories, and cede the Sixteen Prefectures to the Song, and forswore making unilateral peace with the Liao. In 1121-23, the Song faltered in their military campaigns but the Jurchen Jin succeeded in driving the Liao to Central Asia. The Jin handed over several of the Sixteen Prefectures to the Song including modern-day Beijing. In 1125, the alliance ended when the Jin, sensing Song weakness, invaded southward and eventually captured the Song capital of Kaifeng in 1127.