evidence: Looking to the modern era, the South China Sea became an area of contention starting in the 19th century when Vietnam, China, and European colonial powers such as France began to attempt to establish their sovereignty over the Paracel and Spratly Islands. Vietnamese King Gia Long and his successors dispatched flotillas to establish markers and Vietnamese sovereignty on the islands. This was followed by French expeditions in the 19th century. China also formalized its claim in the late 19th century, protesting SCS claims by Vietnam and its colonial power France by sending expeditions to the islands in 1903 and 1907. After serving as a strategic Japanese naval base in World War II, the fate of the Paracel and Spratly Islands remained in limbo. Using this ambiguity over sovereignty, in 1947, China’s nationalist government formally published what is now known as the "nine-dash line," which claimed that China’s sovereignty encompassed practically all of the SCS. The conflict then turned violent in 1974 and 1988 at the instigation of China. Chinese naval forces took control of the Paracel and parts of the Spratly Islands through violent skirmishes with South Vietnam (in the case of the Paracel in 1974) and Vietnam. [...] This historical context proves both the geopolitical and trading importance of the South China Sea. It also shows that the Paracels and Spratlys are deeply rooted in the historical tradition of the countries that border them.