Around 400 years ago, two groups of runners — one Dutch, one French — are said to have set off from the same point on the Caribbean island of Saint Martin to trace the border between their nations.

Starting from a bay on the east coast and running in opposite directions, the runners in 1648 eventually met on the west coast of the island, with a straight line between the two points forming the international border ever since.

According to the legend, the Gallic runners were faster, handing France by far the larger share of the roughly 90-square-kilometre (35-square-mile) tropical paradise, which they called Saint Martin.

The Netherlands took the southern part, which they named Sint Maarten, with the athletic feat and the peaceful coexistence of the two colonial powers leading to the territory being dubbed the “friendly island”.

The agreement was signed for France on Friday by Interior Minister Gerald Darmanin and for the Netherlands by Silveria E. Jacobs, prime minister of the autonomous government of Sint Maarten.

“This historic agreement will help facilitate the process of rebuilding the island, which was severely affected by Hurricane Irma in 2017,” the French interior ministry said in a statement.

The text of the agreement “preserves the principle of free movement of goods and persons established by the Concordia accords of March 23, 1648”.

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The agreement also “establishes a joint monitoring commission charged with monitoring and maintaining the border” which had been disputed at its eastern end.

“It illustrates the quality of the friendly relations between France and the Netherlands, eager to reinforce their trusting cooperation on the island of Saint Martin,” it said.

It stressed “the shared desire of the territorial council of Saint Martin and the autonomous government of Sint Maarten to continue to develop their close ties and their joint projects of cross-border cooperation,” it said.

Darmanin is due to travel to Saint Barthelemy, the other island in the north of the French Caribbean.

The island of Saint Martin is divided in two, with a French community in the north and a state under the Dutch kingdom in the south, Sint Maarten.

France’s half of Saint-Martin became a French overseas territory in its own right in 2007, having previously belonged administratively to Guadeloupe, France’s biggest possession in the Caribbean.

It had a population of just over 32,000 in 2020.