Tref Alaw is a community — the Welsh equivalent of a civil parish — wrapped around the western and southwestern shores of Llyn Alaw, a man-made reservoir built in 1966 to supply drinking water to Anglesey. It is the largest body of water on the island. The community is more a network than a place: a wide spread of farms and five small settlements — Llanddeusant and Elim close together in the centre, Llantrisant a mile to the southwest, Llanbabo in the northwest, and the tiny hamlet of Llechgynfarwy in the south, whose principal building is the medieval church of St Cynfarwy. The 2001 census recorded 606 inhabitants. By 2011 it had dropped to 581. This is countryside that empties as much as it fills.

The northern part of Tref Alaw is dominated by the Llyn Alaw wind farm — 35 turbines turning over a landscape that has been worked by humans for at least four thousand years. The juxtaposition is not as strange as it sounds: every generation in this place has built into the wind. West of Llanddeusant stands Melin Llynon, Anglesey's only working windmill, built during the Napoleonic Wars and milling grain until a storm wrecked its sails in 1918. It fell into ruin, was bought by Anglesey Borough Council in 1976, and was restored to working order in 1986. Beside it now stands a reconstruction of an Iron Age roundhouse. A short way off is Melin Hywel, a watermill restored twice — in 1975 and again in 1985 — and now once more falling into disrepair. The wind, the river, the turbines: three different ways the same landscape has tried to convert moving air and falling water into bread, electricity, and a living.

There are four protected ancient monuments in the community. Glan-Alaw Standing Stone, presumed Bronze Age, sits massive in a field 400 metres west of Bod-deiniol farm. Tregwehelydd Standing Stone — also known as Maen y Gored, the rock of the weir — is around eight feet high, in the care of Cadw. It split along its bedding planes at some point in the past; in 1969, its three pieces were bolted back together with metal straps and set upright in a concrete base. A second slab of similar size lies horizontal nearby, perhaps once part of the same monument. Bedd Branwen, the round cairn east of Elim, contained three cremation urns of the original Bronze Age interments, along with beads, amber, and carved jet; four more cremation burials were added later. And on the hilltop between Elim and Llantrisant, Y Werthyr Hillfort once had imposing earthwork ramparts that have mostly been ploughed away — the Iron Age inhabitants of the inland uplands of Anglesey, watching the country roll out below them.

The Mabinogion gives Branwen one of the saddest stories in Welsh literature. Married to Matholwch, king of Ireland, mistreated and humiliated, she sends a starling across the sea with a message that brings her brother Bran the Blessed and the war-bands of Britain to her rescue. The war destroys both Ireland and Britain. Of the eighty thousand who set out from these islands, only seven men return. Bran himself, mortally wounded, asks for his head to be cut off and carried to London. Branwen lands on the bank of the Alaw with her surviving brother, sees the wreckage of the two kingdoms she has accidentally set against each other, and dies of grief. The story is a thousand years old; the cairn is twice that age. They belong together in this place not because the chronology fits, but because the same instinct — to mark a death beside this river — has run through it for so long.

Most days, Tref Alaw is sheep. It is small farms, narrow lanes, the long horizon of Llyn Alaw under the slow turn of the turbines, the smaller mass of the Carmel Head peninsula in the distance. Llanddeusant has a tiny church. Elim is a scatter of houses. Llantrisant has its own equally small church and not much else. Llanbabo's medieval church holds an effigy that may represent a sixth-century king. Llechgynfarwy's St Cynfarwy's, perched on a hill, looks out across most of north-central Anglesey. None of this is a tourist destination. It is the everyday Welsh countryside that supports an island, supports a language, and has supported communities of one kind or another for the four thousand years since whoever raised the central stone at Bedd Branwen first stood here in the wind off the lake.

Tref Alaw centres at 53.335°N, 4.459°W, on the low ground in the western interior of Anglesey. From the air the defining landmark is Llyn Alaw itself — a long, irregular reservoir with the cluster of wind turbines turning along its north shore. The reconstructed Melin Llynon windmill stands out as a white tower west of Llanddeusant. RAF Valley (ICAO EGOV) lies only 14 km to the south, and the runways are often clearly visible. Holyhead Mountain rises 16 km to the west; the north coast of Anglesey is 10 km north. The community sits roughly central on the island, away from the dramatic coasts that most aviators photograph, but the relationship between reservoir, turbines, and prehistoric monuments is unusually compact.