In the port town of Tanmen, on China's southernmost province of Hainan Island, I met 35-year-old Wang Zhenzhong. He's done pretty well for himself. He graduated from college in Beijing and he runs his own business, selling handicrafts related to the town's maritime culture. He likes to play the guitar.
Like many folks here, his ancestors were fishermen. But one thing that makes Wang different from his neighbors is that he and his family are in possession of something very ancient and very rare.
It is a book, at least six centuries old, that's central to the identity of people in this town, and to China's territorial claims to the South China Sea. Those claims include islands that China's neighbors — Vietnam, the Philippines, Brunei, Malaysia and Taiwan — also say belong to them.
"For thousands of years," Wang says, "fishermen have fished our ancestral sea, the South China Sea, with no more advanced technology than this book, a sailboat and a compass."
The title can be roughly translated as The Book of Maritime Routes. Many Chinese boat captains used to own copies, but now only a dozen or so remain.
The historical argument is important to the dispute. But China is not the only one to use it. Other issues of geography and law are also crucial.
The atmosphere in Tanmen has become more tense since an international tribunal in the Hague announced that it would release a ruling on July 12 in a lawsuit brought by the Philippines, challenging China's claims to much of the South China Sea.
The ruling is widely expected to be unfavorable to China. Beijing says it will ignore the ruling, a move that is likely to be seen as a challenge to the U.S.-dominated strategic order in Asia.
A bit like an almanac, the Book of Maritime Routes contains sections on navigation, weather, currents, medicine and other information useful to fishermen and sailors.
Wang says his dad keeps the family's original copy under his pillow at home. Wang shows me a photocopy that he keeps in his own private museum of maritime artifacts.
Together, he and I read a passage that describes how to get to an island in the Paracel chain, about 190 nautical miles southeast of Tanmen. The Paracels are claimed by both China and Vietnam.
This book shows that fishermen from his town named those islands, using their own local dialect, Wang says.
"This is the most compelling evidence that the South China Sea belongs to China," he says. "For 3,000 years or more, our ancestors have been fishing in these waters just like in their own home."
Wang says his grandfather's grandfather perished at sea, but that didn't make his family afraid of the wind or the waves — or stop them from fishing in every major island chain in the South China Sea, hundreds of miles and several days' journey by boat from Tanmen.
"Even after someone dies at sea, fishermen will sail to waters even farther away," he declares. "This is the spirit of Tanmen people."
At this time of year in Tanmen, many fishing boats are in the docks for repairs. A fishing ban from May to August gives the fish populations some time to recover.
Only a few decades ago, the town's docks were mostly lined with wooden sailboats. Now many of them are 100-ton steel trawlers with electronic navigation systems. The government subsidizes the building of these boats. It has also recruited many of the fishermen into maritime militia units.
Near the docks, a billboard shows a picture of President Xi Jinping talking to local fishermen and praising their vanguard role in protecting China's maritime rights and interests in the South China Sea.
Critics charge that China has used these militia forces to build up artificial islands and reefs, to harass the ships of its Southeast Asian neighbors and the U.S.
Chinese fishing trawlers — possibly belonging to militia units — reportedly crossed the bow of a U.S. destroyer, the USS Lassen, as it conducted freedom of navigation operations in the South China Sea last October.
Chinese militia boats also rammed and destroyed Vietnamese trawlers in a fight over a Chinese oil rig operating in waters claimed by both China and Vietnam near the Paracels in 2014.
China and Vietnam both have maritime militias, notes Andrew Erickson, a professor of strategy and expert on China's navy at the U.S. Naval War College. He accuses China of trying to create confusion about whether the militia forces are military or civilian.
"By obfuscating and having these forces lurk in the shadows," he argues, "China's trying to have it both ways in a way that doesn't accord with international law."
Erickson says there should be no confusion: The militia takes orders from China's military.
"It's high time that the U.S. made statements in advance so that it's clear to everybody that the U.S. is wise to China's game," he says, and that American naval vessels will not be deterred by the militia as they carry out their operations in the South China Sea.
When asked to clarify the status of the maritime militias, Chinese Ministry of Defense spokesman Yang Yujun did not respond directly, saying only that the militia forces engage in fishing and "maritime rights protection" activities in accordance with Chinese law.
The U.S. is not about to give up the strategic dominance it has enjoyed in the western Pacific for the past century or so. And China is no longer content with that arrangement.
Regardless of what the Hague tribunal rules on Tuesday, the U.S. and China — including its fishermen and militias — are likely to be in closer, more frequent contact as both sides beef up forces and jockey for strategic advantage in the South China Sea.
For that reason, Erickson suggests that the U.S. needs to learn more about local Chinese actors and institutions and their roles in the dispute.
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