When Roman writers described the Frisii in the first century, they were a people of forests and cattle, scattered across the coast from present-day Bremen to Bruges. They halted a Roman advance. They appeared in Tacitus as having kings only as far as the Germans are under kings - meaning barely. Then the coastal floods of the Migration Period nearly emptied the land. New Frisians moved back in, merged out of Angles, Saxons, Jutes and the older Frisii, and resumed the same loose tribal arrangement. While the rest of feudal Europe stratified into lords and serfs, Frisia did not. The free peasants elected representatives called redjeven and resolved disputes through judges called Asega. The arrangement lasted, in slowly eroding form, almost a thousand years. The Dutch historical memory still calls it Frisian freedom.

It ended in two pieces. The first was the Battle of the Boarn in 734, when Charles Martel ferried a Frankish army up the river and broke the power of the Frisian kings for good. The Carolingians annexed the land between the Vlie and the Lauwers; Charlemagne finished the job further east. The second ending came almost eight centuries later, in the 1510s, when a farmer named Pier Gerlofs Donia watched a Habsburg-employed Landsknecht regiment burn down his farm and kill his kin. He raised a peasant army - the Arumer Zwarte Hoop - and fought back. He was a giant of a man whose sword still hangs in the Fries Museum, and for a few violent years he was the public face of Frisian resistance to Habsburg rule. He died in 1520. The rebellion collapsed by 1523. Frisia was incorporated into the Habsburg Netherlands, and Frisian freedom became a memory and a story.

Some peoples preserve themselves through architecture. The Frisians did it through language. West Frisian is the native tongue of just over half the province's inhabitants and is closer to Old English than to Dutch - a fact that traces back to when Angles, Saxons and Frisians crossed the same coast to populate Britain. In 1996 the provincial council voted to make Fryslan, the West Frisian spelling, the official name of the province. The Dutch government confirmed it in 2004. Children receive a taaltaske at birth - a language gift bag with information for parents about raising bilingual kids. The Fryske Akademy in Leeuwarden publishes a twenty-five-volume Frisian dictionary. West Frisian is mandatory in primary schools across the Frisian-speaking districts. The language is being kept alive the way a coastal village keeps a dyke - constantly, by everyone.

The black Frisian horse, with its waterfall of mane, was bred here. So was the black-and-white Frisian cow, the ancestor of Holstein cattle that now produces dairy on every continent. So was the Stabyhoun, a friendly black-and-white hunting dog so local that nearly all of them in the world live in Friesland. The traditional sports are equally rooted. Skutsjesilen pits flat-bottomed sailing barges - skutsjes - against each other across the Frisian lakes each summer. Fierljeppen is competitive canal-vaulting: athletes sprint at a long pole, leap and grab it, climb it as it tilts across the water, and try to land gracefully on a sandbank on the far side. And then there is the Elfstedentocht, the legendary two-hundred-kilometre skating tour past eleven cities that only happens when nature provides the ice - last in 1997. A province with its own horse, dog, cow and a national sport that requires a pole and a canal is not trying to blend in.

From cruising altitude Friesland looks like a green grid laid out on water. There are roughly twelve hundred windmills in the Netherlands; one hundred ninety-five of them stand here, marking the polders where they once pumped the land dry. The Wadden Sea unrolls along the northern coast, a UNESCO-listed shallow tidal flat dotted with the long thin islands of Vlieland, Terschelling, Ameland and Schiermonnikoog. The southwest dissolves into the lakes - twenty-four of them in the Frisian Lakes alone, threaded by canals. In the centre sit the eleven historic cities of the Elfstedentocht: Leeuwarden the capital, Sneek and IJlst, Sloten and Stavoren and Hindeloopen, Workum and Bolsward, Harlingen on the coast, Franeker, Dokkum in the north. To fly over Friesland is to see the geography of stubborn freedom drawn in water.