Who ruled Tiwanaku?

Tiwanaku is a pre-Columbian city in western Bolivia, on the high plain south of Lake Titicaca, about 70 kilometres from La Paz. Between roughly 600 and 1000 CE it was the capital of the Tiwanaku state, one of the most important civilisations of the Andes, whose influence reached into what are now Peru and Chile. Its stone platforms, sunken courts and carved gateways, among them the Gateway of the Sun, make it one of the largest archaeological sites in South America.

The age of the site has been argued over for a century. Between 1910 and 1945 Arthur Posnansky claimed it was 11,000 to 17,000 years old, and from the 1970s Carlos Ponce Sanginés proposed a first occupation around 1580 BCE. Both views have been abandoned. Scholars now agree that the site is no older than about 200 or 300 BCE, and a recent statistical study of reliable radiocarbon dates places its founding around 110 CE.

The city grew steadily in the first centuries CE and became a major centre between about 375 and 700. At its height it covered some four square kilometres; a cautious estimate puts its population at 10,000 to 20,000 around 800. Its wealth rested on farming and herding on the high plain, including raised fields that probably fed the urban population, and on trade. The people of Tiwanaku left no writing, so the name they used for their city is unknown; a later chronicler recorded the Aymara name Taypiqala, "stone in the centre". The linguists Heggarty and Beresford-Jones suggest that its people probably spoke Puquina.

At the heart of the city stood a group of monumental buildings: the Akapana, a terraced platform mound about 16.5 metres high; the T-shaped Pumapunku, faced with huge cut stones, the largest estimated at 131 tonnes; the Kalasasaya enclosure; and a Semi-Subterranean Temple whose walls are studded with carved stone heads. Excavations at the Akapana found sacrificial offerings of people and llamas. The Gateway of the Sun, which now stands in the Kalasasaya, is probably not in its original position. The front-facing figure carved on it has been linked to the creator god Viracocha of later Inca belief, but this remains speculation.

Tiwanaku shared its religious imagery with the Wari culture of the Peruvian highlands, its great contemporary, though whether their contacts were peaceful or warlike is unknown. Some archaeologists argue that Tiwanaku established colonies well beyond the plain, notably in the Moquegua valley of southern Peru.

Around 1000 CE the production of Tiwanaku pottery stopped, and both the capital and its largest colony in Moquegua were abandoned within a few decades. A long drought that ruined the raised-field farming has often been blamed, but more refined dating has cast doubt on this account, and some scholars point instead to internal conflict. Parts of the city show signs of deliberate destruction: gateways were toppled and broken, and the Putuni complex was burned.

The ruins enter the written record in 1549, when the Spanish conquistador Pedro Cieza de León described them. In the centuries that followed, through the Spanish colonial period and into the twentieth century, the site was looted, dug over by treasure hunters and quarried for stone for buildings and railway construction, and soldiers even used it for target practice. No standing buildings survive.

Serious study began in the nineteenth century with maps and drawings by travellers such as Ephraim Squier and Alphons Stübel, and in 1892 the photographs of Georg von Grumbkow, with commentary by Max Uhle, formed the first detailed scientific account. In the 1960s the Bolivian government rebuilt parts of the site, especially the walls of the Kalasasaya, with limited regard for the original evidence. From 1978 Alan Kolata of the University of Chicago and his Bolivian colleague Oswaldo Rivera led modern excavations. In 2009 work facing the Akapana with adobe was stopped after objections from UNESCO, which had listed Tiwanaku as a World Heritage Site in 2000. Drone surveys in 2016 revealed many previously unknown structures around the core. The site is administered by the government of Bolivia, and the Aymara people who live around it are thought to descend from the people of Tiwanaku.