Archaeologists have discovered the ruins of an ancient city that they hope might finally answer questions about the fate of the Moche culture — best known for the ceremonial sex acts and ritualistic human sacrifices depicted on its pottery.

The unearthed city is some 5km (three miles) long and has revealed what appears to be a gathering place for human sacrifices, a heap of human bones at the bottom of a cliff, ceramics, items of clothing and the well-preserved remains of a young woman.

Archaeologists hope that the ruins will provide the missing link between the Moche people — whose disappearance has long since puzzled historians — and the Wari, who later colonised parts of what is today Peru.

"[The city] provides the missing link because it explains how the Wari people allowed for the continuation of culture after the Moche,” said César Soriano, chief archaeologist on the excavation project, 22km from the Pacific coast city of Chiclayo.

The Wari ruled the country now known as Peru from about AD600 until about AD1100. Nevertheless, it is the Moche who often inspire the greater fascination, largely because of their wildly exotic rituals and artefacts, such as their erotic ceramics, which depict ceremonial sexual encounters, performed in specially constructed temples in front of witnesses (who are shown holding hands as if in prayer).

Moche ceramics also depict ceremonial human sacrifice and blood drinking, with victims being subjected to excoriation (skinning), decapitation and bloodletting. It is thought that cannibalism probably also took place.

The reason for the Moche’s demise in the early 9th century — after flourishing for 700 years — is a continuing mystery. Scholars believe that the various autonomous tribes which comprised the Moche (connected by a common elite culture) could have been ravaged by a super El Niño — perhaps 30 years of intense tropical downpours followed by another 30 years of drought — and then fallen victim to a protracted civil war.

So far no evidence has emerged to show that the Wari invaded Moche settlements. Nevertheless, it is known that the Wari people — who first established themselves in the central Andes, far from the Moche on the Pacific coast — excelled at using military force to make territorial acquisitions and then to impose their culture on defeated populations.

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