Han led an invasion fleet to Annam to assist Kiều Công Tiễn. Dương Đình Nghệ's son-in-law Ngô Quyền, also was from the south, marched north and killed Kiều Công Tiễn. He then led the people to fight and destroyed the Southern Han fleet on the Bạch Đằng River. After defeating the Southern Han invasion, Ngô Quyền proclaimed himself king and established a new dynasty in Cổ Loa citadel over the Principality. Cổ Loa's sphere of influence probably did not reach the other local nobility. In 944, after his death, Ngô Quyền's brother-in-law Dương Tam Kha (son of Dương Đình Nghệ) took power. The Dương clan increased factional segregation by bringing more southern men into the court. As a result, the principality broke apart during the reign of Tam Kha. Ngô Quyền's sons Ngô Xương Văn and Ngô Xương Ngập deposed their maternal uncle and became dual kings in 950. In 954, Ngô Xương Ngập died. The younger Ngô Xương Văn ruled as the sole king, and nine years later he was killed by warlords. Chaos unleashed across the Red River Delta. Early Đại Việt A new leader of prowess named Đinh Bộ Lĩnh emerged. From Hoa Lư, he and his son Đinh Liễn spent two years in political and military struggle and managed to subdue all warlords and oppositions. Around 967 or 968, Đinh Bộ Lĩnh established the kingdom of Đại Cồ Việt (大瞿越) (meaning "The Great Gau(tama)'s Việt"), and moved the court to Hoa Lư. He (r. 968–979) became king of Đại Cồ Việt and titled himself emperor, while Prince Đinh Liễn became the great prince. In 973 and 975, Đinh Bộ Lĩnh sent two embassies to the Song dynasty and established relationships. Buddhist clergy were put in charge of important positions. Coins were minted. The territories of the early Việt state comprised the lowland Red River Basin to the Nghệ An region. According to a Hoa Lư inscription (c. 979), in that year Đinh Liễn murdered his brother Đinh Hạng Lang who had been promoted to crown prince by his father. In late 979, both Đinh Bộ Lĩnh and Đinh Liễn were assassinated. Hearing the news, Ngô Nhật Khánh, a prince of the old royal family in exile-and king Paramesvaravarman I of Champa launched a naval attack on Hoa Lư, but much of the fleet was capsized by a late-season typhoon. Queen Dương Vân Nga placed her partner,