Above left Moment of discovery. One of the masks emerges from the earth in the subterranean complex.

The curious case of the Gua Made green masks

Sensational discoveries of metal masks in a subterranean temple have led to calls for Javanese history to be rewritten. Fiorella Rispoli investigates.


About ten years ago a collector of ancient Indonesian art contacted my husband and me to ask our opinion on a group of masks cast in an odd green metal in his possession. Some of these masks, he said, had been recovered from an underground temple in a remote site called Gua Made, north of the Brantas River in East Java.

I was immediately sceptical, and became steadily more so when the collector announced that ‘the masks are more than 3,000 years old’. This date was based on thermoluminescence (TL) analysis of a terracotta brick from the ‘underground temple’. Assuming a temporal association between the masks and temple, the collector went on to propose that both could be the product of a lost civilization. Sounding like the plot of a pulp archaeological thriller, it contained the ingredients of a classic mystery: amazing ancient masks made from a mysterious metal, found in an exotic underground ‘temple’ that was sacred to a forgotten culture. All that was missing was publicity.

Above left Moment of discovery. One of the masks emerges from the earth in the subterranean complex.
Moment of discovery. One of the masks emerges from the earth in the subterranean complex.

Not anymore. A recent article by A M Steiner and M Vidale in the pages of the renowned Italian magazine ARCHEO, supports dating the green masks to the early 1st millennium BC. They subscribe to the notion of a lost civilization, observing that the discovery of the masks and their date rewrites the archaeology of Island Southeast Asia, ‘opening a new, unexpected page of the fascinating book of the Eurasian lost past’.

To many authorities on the archaeology of Southeast Asia, this date seems far too early. It was a thousand years later that a great ‘classical’ civilization arose, based on Buddhist ideals. Could these new discoveries really antedate this civilization? Or was there another explanation? These questions came to concern me personally when Italian diplomatic authorities in Indonesia took an interest in the Gua Made masks. This led to the Italian Institute for Africa and the Orient (IsIAO) appointing me to direct an excavation campaign at the site. In July 2007, therefore, in full agreement with all the relevant Indonesian authorities, I began my first field season at Gua Made.

Setting the scene

The discovery of the site is controversial, and various witnesses have provided differing statements about the circumstances. The facts, so far as they can be established, are these: following initial looting, two short excavations were conducted by the Bureau for the Archaeological Conservation of East Java (BACEJ). Funded by the collector who acquired the masks, these ran for six days in 2001, and two weeks in 2006. In the process, four vertical shafts were emptied. Covered by brick vaults, these shafts were connected by corridors cut through the bedrock at a depth of about 7m below ground level. Finds included imported glazed pottery, Chinese copper or bronze coins and, of course, the striking green masks.

Our 2007 excavations focused on two areas: to the north of shaft 4, and south of the emptied shafts 1 and 2. Examination of the section visible in the sides of the trench sunk in 2006 revealed that the entire archaeological deposit lay within a large artificial ditch that had been cut into the natural sandstone. Stratigraphic excavation of this deposit revealed a previously overlooked shaft.

Above A selection of the Gua Made masks after cleaning.
A selection of the Gua Made masks after cleaning.

The main discovery in the trench around shafts 1 and 2 was a length of brick roofing. This was evidently part of a corridor that linked shaft 1 to a room that must lie to the south of the excavated area. The roof structure consisted of four overlapping rows of clay bricks that had been cut into the natural bedrock.

There can be no denying the monumental nature of the remains. A complex subterranean structure such as this would have required mass community involvement. Digging the ditch around shaft 4 would, in itself, have been a considerable endeavour, occupying an appreciable workforce. The structure as a whole is a most impressive public work, and certainly longer than the 60m so far traced, while the overall layout displays a sophisticated integrated design. Excavation demonstrated all of this. But two crucial questions still remained, what was this integrated design intended to achieve, and when was it built? To tackle these questions in reverse order, let us start with the crucial matter of date, on which all claims of a lost civilization hang. This leads us in turn to the TL date from the shaft brick that lies at the heart of this controversy. It is this alone that consigns the complex to the first millennium BC. But is it a smoking gun?

right Inside the underground complex in which the masks were found.
Inside the underground complex in which the masks were found.

Island of Barley

To appreciate the seismic implications of the TL date, we must set the scene by investigating the accepted model for social development on the island at the heart of this case: Java, known to the ancients as Yavadvipa, the Island of Barley. Long before Hellenic and Roman geographers learnt of the Indonesian archipelago, merchants and sailors from India, accompanied by Hindu and Buddhist missionaries, had ventured to the islands and coasts of Southeast Asia. The fascination and riches that this island paradise excited in the minds of the traders is perfectly captured by the ancient Indian author of an unashamedly Machiavellian treatise known as the Arthasastra:

Who goes to Java never returns
If by chance, he returns,
Then, for seven generation, money enough
To live upon, he brings back.

Abundant artefacts of Indian origin from numerous sites testify to an enthusiastic pursuit of the proffered seven generations of wealth.

top The corbelled brick ceiling of the subterranean structure. Above The position of our 2007 trenches, alongside the known shaft positions.
The corbelled brick ceiling of the subterranean structure.
The position of our 2007 trenches, alongside the known shaft positions.

Dating from the later 1st millennium BC to the 4th century AD, Indian imports are especially copious along river valleys and coasts. Their presence suggests that regional elites embraced long distance contacts, and even adopted aspects of Indian culture to further their own ends. Monopolising access to these prestigious imports provided local rulers with an opportunity to secure their power base, assisting the birth of the many ‘Indianised’ kingdoms of Southeast Asia that sprang up around the mid-1st millennium AD. These states blossomed between the 6th and the 13th centuries – a period characterised by exquisite temple architecture. However, this cultural epiphany was only made possible by an enthusiasm for all things Indian, fuelled by considerable surplus wealth. This lay in the hands of aristocrats who, on the mainland as well as the major islands, grew rich off the back of an agricultural system based on rice cultivation and long distance trade with the West, via India, and, more directly, with China.

right The huge artificial ditch that was cut in order for the structure to be constructed is visible in the section of the trench. The opening of Shaft 4 lies within the trench.
The huge artificial ditch that was cut in order for the structure to be constructed is visible in the section of the trench. The opening of Shaft 4 lies within the trench.

These Southeast Asian kingdoms have left a rich archaeological legacy. The ruling elite of the fledgling states in Central Thailand were among the first to express their status through the construction of magnificent temple complexes. Dating to the 6th-10th centuries AD, in many ways the ensuing temples are a physical tribute to the scale of Indian influence, drawing heavily on Hindu and Buddhist elements. Elsewhere, Java’s neighbour Sumatra developed into a major regional power in the 7th century. But even this commercial powerhouse pales in comparison with Angkor in Cambodia. Here, between the 9th and 14th centuries, all-powerful god kings presided over the development of what is arguably the largest preindustrial city in the world, containing hundreds of exquisite temples.

So what of Java itself? By the 7th-8th centuries the ruling class in Central Java had certainly adopted Indian trappings such as Sanskrit names and the Hindu or Buddhist religions. The Hindu Sanjayas took power around AD 732, only to be succeeded by the Buddhist Sailendras in 778. The rise and fall of these ruling families marks the Central Javanese Period (AD 732-928), a time when the first temples were erected in southern Java, at the foot of the Merapi volcano. This dovetails with the general pattern of temple building across Southeast Asia in the six centuries astride the dawn of the 2nd millennium AD. In Java this ‘time of grace’ is showcased by a Buddhist stupa: the Borobudur. This was built between AD 780-830 under the aegis of the Sailendra family.

The Buddist Borobudur in Java. Built between AD 780 and 830, it is one of the finest temples in Asia. The terraces are symbolic of the steps to

Time of Grace

The Sailendra family and their monuments had a far-reaching impact. Even the Khmer sovereigns, renowned builders of the magnificent temple-mountains at Angkor (10th-13th century), were in their debt. The man who became the first architect of the Khmer empire, Jayavarman II, had spent his youth at the Sailendra court. Returning to Cambodia fully indoctrinated with Indonesian cultural concepts, he assumed an identical title to the Sailendras, that of ‘King of the Mountain’. The Sailendras certainly played up to this conceit, commissioning temples that reached far into the sky, rather than delving deep underground.

In East Java itself, home to the enigmatic subterranean structure that housed the metal masks, the earliest uncontested architectural remains are two 8th-9th century AD temples. The 10th and 11th centuries were a time of conflict on the island, against enemies both within and without. Eventually, a local ‘prince’ united Java, but it was not until 1222 that a new dynasty brought new temples. The real explosion in construction followed in the Majapahit period (1292-1500). For two centuries this dynasty held sway over first East Java, and then the entire island. The heart of their new kingdom was at Trowulan in East Java, where the capital grew to cover an astonishing 100km2, including palaces, sacred bathing places, pools, temples and houses connected by an ingenious network of canals and reservoirs. But it was not to last.

Above A small ornamental mask. Found with the green masks, and made of the same material, this can be dated on stylistic grounds to the 13th or 14th century. Aboveright A length of brick roofing under excavation.
A small ornamental mask. Found with the green masks, and made of the same material, this can be dated on stylistic grounds to the 13th or 14th century.

Between the 14th and 15th centuries, Islam spread from Malacca to Sumatra, and then to Java, bringing an end to the great Majapahit kingdom. Looking at this panorama of high-rise temples, built over a millennium across Southeast Asia, how do we explain the presence of the isolated ‘underground temple’ discovered at Gua Made in East Java?

Essentially, there are two serious stumbling blocks when it comes to reconciling the new discoveries with current understanding of Javanese history. As we have seen, monumental architecture is unknown in East Java before the 8th or 9th century AD. Is it really possible that such a structure could have been constructed almost two millennia earlier? Equally conspicuous is the lack of any kind of indigenous tradition of underground temples.

A length of brick roofing under excavation.

What‘s in a date?

Both of these problems stem from the TL date. But while this is referred to as a ‘scientific’ or ‘absolute’ dating technique, the method is not without its limitations. Science can excite a powerful grip on the minds of the unwary, but the truth is that rigorous procedures need to be carefully observed, including gathering exact measurements of radioactive levels in the environment, if there is to be any hope of an accurate date. Even then Indonesia falls alongside West Mexico as a region that is notorious for unreliable TL dates due to the poor susceptibility of local materials. On this basis alone one would be wise to tread carefully after receiving a dating result that is starkly contradicted by all accepted local chronologies.

Of course, scientific techniques are only one way of dating archaeological deposits. Another tried and tested approach is to use the artefacts themselves. The sensation caused by the masks often eclipses the other material found in the underground complex, resulting in the valuable dating indicators they provide being overlooked. The very use of the brick which yielded the TL date cannot currently be dated earlier than AD 500 anywhere in Island Southeast Asia. In Java the earliest accepted use of terracotta bricks dates to the 6th century AD, indicating limited use in the Central Javanese period. However, the introduction of brick to East Java cannot yet be dated earlier than the 11th century, and the building material is nowhere in common use prior to the Majapahit period (1292-c.1500). Like the monumental temple complexes they were routinely used to construct, there is currently no supporting evidence to extend their presence back into the 1st millennium BC.

below The underground complex at Gua Made, seen in cross section.
The underground complex at Gua Made, seen in cross section.

The artefacts found inside the structure tell a very similar story. These finds, all datable to between the 11th and 15th centuries, include imported 13th- to 15th-century Chinese porcelains and a small ornamental head, which should on stylistic grounds date to the 13th or 14th century. Tellingly, perhaps, this was cast from the same mysterious material as the green masks. While Steiner and Vidale argue in their ARCHEO paper that this assemblage does not provide decisive proof of date, its implications can hardly be simply swept under the carpet. On the contrary, far from being a red herring, it constitutes the most powerful evidence available to assign the contents of the underground complex to a specific period; a period that enables us to lose the lost civilization.

Dating the subterranean structure provides a context in which we can attempt to deduce its purpose. After all, an underground temple would be conspicuously outside the regional norm, no matter when it was built. The period between the 13th and 15th centuries coincides with the extensive building projects, both sacred and secular, initiated under the ruling Majapahit dynasty. Further tantalising clues to the purpose of the subterranean facility came to light in 2007: first a small pool, or tirtha, with brick facing was detected near the southwest corner of the site; then several wells were found along the slope of the plateau to the southeast. Both discoveries show a preoccupation with water.

top A green-metal spiral eyed anthropomorphic figure compared with a brass figurine with simialr eyes from Central Sulawesi (18th century AD). Above A diagram showing the workings of a typical qanat.
A green-metal spiral eyed anthropomorphic figure compared with a brass figurine with simialr eyes from Central Sulawesi (18th century AD).
A diagram showing the workings of a typical qanat.

When shown in cross-section, the underground complex bears a striking resemblance to a form of water transport system known as a qanat in Arabic. Such devices extract water from an aquifer by driving multiple vertical shafts into the ground and then linking them by a subterranean channel. The gently sloping channel conveys water to an outlet at the end of the qanat without requiring pumping, and could easily be mistaken for an underground corridor. On this basis I suspect that the complex of shafts and corridors at Gua Made was a system for water collection and transportation. This hypothesis certainly requires further field-testing, but the close structural resemblance between the two water systems cannot be ignored.

Masking the truth

This leaves the green masks themselves. What of their chronology, function, and material? In a way, referring to them exclusively as masks is a misnomer, as they can be divided into three groups: human-like bust figures; animal or human-and-animal figures; more naturalistic ‘portrayal’ masks. I have included busts (either realistic or geometric) that have human-like faces bearing exaggerated or distorted features into the first group. Their enigmatic and crude expressions, what Steiner and Vidale refer to as a ‘disturbing archaic vitality’, bear much of the blame for the fascination that this find has produced.

right Ancestor figurines with grotesque features from the Island of Flores.
Ancestor figurines with grotesque features from the Island of Flores.

There are parallels for such grotesque features in Island Southeast Asia. Ancestor (or idol) figurines from the Island of Flores have an equally ‘archaic effect’. These figures, cast from rather unconventional alloys (‘brass’ and silver amalgam), can be dated to the 18th-19th centuries. During the 1970s, figurines of this kind were still regarded as heirlooms, and it is recorded that they were generally concealed from outsiders. Bearing this in mind, a case could be made for the Gua Made masks being deliberately stashed within the abandoned underground conduits relatively recently. However, the consistently earlier date of the accompanying material might simply reflect the danger of taking stylistic similarities too far.

The full-round ‘green sculptures’ of the 2nd group feature decorative details or themes that can be traced back to the Hindu-Buddhist art of East Java. These belong to the period when Hinduism and Buddism merged in an act of religious syncretism, a process that began in the thirteenth century AD. I would not be surprised if art-historians ultimately demonstrate that the figures from Gua Made are folk versions of the more refined religious sculptures produced by professional craftsmen for temple complexes.

Most of the ‘portrayal masks’ in the 3rd group reproduce individual faces in a refined and accurate naturalistic style. The style of the masks, if not the material from which they are made, recall the varying expressions of the masks worn when performing the Wayang orang, a form of dance theatre that is not recorded before AD 930.

An example of the third style of mask from Gua Made, showcasing the naturalistic style.

The final element of the mystery that we must unravel is the question of just what the masks are made of. An esteemed Italian archaeo-metallurgist is currently carrying out analysis of the metal, and has described his provisional results as revealing not ‘a “metal” strictly speaking, but a kind of material decidedly more complex and uncommon … that … does not find comparisons in Europe, the Middle East or Central Asia’.

In 2007, I received from an associate the results of the preliminary analyses carried out on samples taken from the ‘green masks’. These data reveal that the masks were made of either an alloy or an unusual amalgam of brass. The source of this alloy is unknown, but it is worth considering the role that hundreds of thousand tons of Chinese copper-based coinage imported to Indonesia between the 11th and the 16th century, might have played. Large numbers of them could have been reused by local charmers-metallurgists, exactly as they did, from the 17th century on, with the mostly Dutch, gold and silver coins entering the region. As for the date of this green metal, in Indonesia the first, scientifically controlled, archaeological evidence of a copper-tin alloy does not pre-date the later 1st millennium BC. Brass appeared a millennium and a half later.

below A full-round, green-metal figure resembling a tower-temple with a Kala head on the doorway.
A full-round, green-metal figure resembling a tower-temple with a Kala head on the doorway.

Case closed

It is in the nature of archaeology that some dating inferences can be no more than circumstantial. Nevertheless, taken together the entire body of evidence, with the exception of the TL date, demands a post-10th century AD origin for the ‘green masks’. Here then, is the denouement to our mystery. The subterranean temple is most likely to have been a water control system, while the green masks were made of brass and can be placed within a tradition of local Indonesian folk practices. The slender evidence for an origin in the 1st millennium BC can be discounted, leaving no room and no need for a lost civilization. Instead we are left with new insights into community infrastructure in East Java, and a group of artefacts that are no less fascinating, or beautiful, for belonging to an era already known to archaeology.

Fiorella Rispoli is Senior Archaeologist and Specialist of Southeast Asian Archaeology at the Italian Institute for Africa and the Orient (IsIAO)..
All images: F Rispoli.