The answer was hiding in plain sight. Peruvian fishermen had always known what archaeologists eventually confirmed: the cold Humboldt Current pushing up the South American coast creates one of the richest marine ecosystems on Earth. Anchovies by the millions. Mussels, clams, and crabs so thick on the rocks you could gather a family's dinner in an afternoon. The people who built Las Haldas between 1800 and 1000 BCE did not farm cereals. They fished, gathered shellfish, and for everything else they traded with the inland valley farmers twelve miles to the north along the Casma River.

The ruins cover about forty hectares on a coastal terrace roughly 120 feet above the sea. The central architecture is a 370-meter U-shaped complex with a massive mound at one end and four elevated plazas stepping down toward the ocean. The largest plaza contains a sunken circular court, a feature that spread across Andean ceremonial architecture for millennia. Eighteen smaller mounds surround the central core, each with its own plaza. Residential zones flank the monumental heart on both sides. This was not a village. It was a planned ceremonial city, oriented to the sea that fed it.

In the 1970s, anthropologist Michael E. Moseley looked at Las Haldas and other early Peruvian coastal sites and made a radical argument. The conventional wisdom, built on Mesopotamian and Egyptian models, held that civilization required cereal agriculture - the surpluses of wheat, rice, or corn that let a few people escape daily food production and become priests, craftsmen, warriors, rulers. Moseley's Maritime Foundations of Andean Civilization hypothesis said the Peruvian coast had done it differently. Here the ocean played the role of the grain basket. Radiocarbon dating supported him: Las Haldas appeared to be older than many of the inland agricultural sites nearby. More recent discoveries at Sechin Bajo have complicated the picture, but in 2004 Moseley was still willing to say that Peruvian fishermen might have created the earliest civilization in the Americas.

If you stand at Las Haldas today, the question presses hard. The nearest fresh water is at least twelve miles away through dry hills. Some archaeologists argue there must have been wells nearby, long silted in. The husband-and-wife team of Shelia and Thomas Pozorski argued the opposite: early Peruvian fishing communities routinely built distant from fresh water because shellfish and fish are more abundant away from river mouths where fresh water dilutes the salinity. Cool coastal temperatures meant low drinking-water needs. Seafood itself is mostly water. Cooking could be done in seawater. Drinking water could be carried on foot from the Casma Valley, the same route that brought in cotton, beans, chili peppers, and lúcuma fruit.

Las Haldas sits within one of the most remarkable archaeological landscapes in the Americas. Sixty miles south lies the Caral-Supe civilization, contemporary with the pyramids of Egypt. The Casma Valley just north holds Cerro Sechin, Sechin Alto, Sechin Bajo, Chankillo - an entire network of pre-ceramic and early-ceramic monuments. Las Haldas probably patterned its Phase 2 construction on the nearby Sechin Alto complex, and in turn may have influenced the coastal communities north of it. These were not isolated settlements. They were nodes in a web of trade, ideology, and construction know-how that stretched along hundreds of miles of desert coast.

After 1000 BCE, Las Haldas was gradually abandoned. Irrigation agriculture was transforming the interior valleys, and with it the balance of power shifted inland. Coastal fishing villages became satellites of the agricultural river communities they had once supplied. The U-shaped platform emptied. The plazas fell silent. What remains is a quiet, windblown site on a bluff above the Pacific - the rocks, the mounds, and the long memory of people who built a civilization on anchovies and shellfish, in a place that should have been uninhabitable.