The Chira River has always shaped life in this corner of Peru's Piura region. When it swelled beyond its banks, the Zapotoleños scattered. Some went to Ventarrones, others to Monte Lima or Alto Grande, but a core group climbed to the raised ground that would become known as Cerro Mocho. Up there, away from the floodplain, they were safe but needed building materials. The hill provided them. Villagers cut stone block after stone block from its flanks and upper ridges, hauling them down to raise walls and roof posts. Over years and decades, the summit simply disappeared into huts. Whether the story is literally true or partly legend, the missing peak stands as evidence enough.

For decades the area answered to Tamarindo, a district in the distant province of Paita. Communication was difficult, official business slow, and residents came to resent the arrangement. On 16 October 1963, deputies Luis Carnero Checa, Juan Aldana Gonzales, and Felipe Garcia Figallo signed a bill to separate the area from Paita and attach it to Sullana. Law 15611 made it official on 10 September 1965, with San Jacinto designated as the new district capital. The transition took time. Santos Oblea, the outgoing governor of Tamarindo, continued in office until the end of 1966 before handing power to Ignacio Coronado Pena, the first municipal governor under the new arrangement. The district took its name from a local figure the residents wanted remembered.

The district sprawls across 306 square kilometers along the eastern bank of the Chira River, just 35 meters above sea level and about 25 kilometers from Sullana. Within that modest area live roughly 14,765 people, scattered through an archipelago of villages and hamlets whose names read like a rosary of rural Peru: Belen, Buenos Aires, La Cancha, Las Malvinas, San Isidro, Monte Lima, San Jacinto itself. Further out sit the caserios, smaller still: Santa Sofia, Ventarrones, Agua Amarga, Algarrobo Seco, Hualtacal, Jaguay Negro, Orejona, Pampa Larga, San Rolando. Each name records a founding family, a landmark tree, a geographic accident. Most residents, though, still call the whole place Cerro Mocho, after the flat-topped hill that saw everything begin.

The climate here is coastal-desert hot, with days ranging between 90 and 100 degrees Fahrenheit most of the year. Rain comes when it comes, unreliable and irregular. Winter brings brief cool nights that drop to around 68 degrees, enough to feel refreshing if you were born here, bracing if you were not. Between the river and the sun, the district has always balanced on a narrow margin. When the Chira is generous, crops flourish in the alluvial soil. When it floods, as it did generations ago, the people remember why their ancestors climbed up from the valley in the first place and look again at the flat top of Cerro Mocho.

The old landowners' houses still sit on the lower slopes of Cerro Mocho, ruins now, roofless and gap-walled, staring out over the district they once claimed. If the hacienda story is the true one, these are the houses for which the peak was meant to be leveled, abandoned when the labor became too great. If the flood story is correct, they are monuments to a later layer of ownership. Either way they share the hillside with the absent summit, with modern roofs in the pueblos below, and with a highway that carries traffic north toward Talara and south toward Sullana, most drivers never noticing the flattened peak or guessing the stories it could tell.