Iron-production sites of the early historic period in Mainland Southeast Asia (fifth to fifteenth centuries AD) are rare. Recent excavations at the Tonle Bak site in central Cambodia now provide the first evidence for furnace technology, metallurgical characteristics of slag concentrations and evidence for the organisation of local smelting communities and ritual practices during the peak of the Angkorian Khmer Empire. The results demonstrate that the smelters were directly integrated with Angkorian state-exchange networks. They also raise questions about the use of ethnohistorical records for understanding the identity and organisation of these early metalworkers.

Inscriptional evidence suggests that the Phnom Kulen plateau to the north-east of Angkor in Cambodia was the location of Mahendraparvata—an early Angkorian capital city and one of the first capitals of the Khmer Empire (ninth to fifteenth centuries AD). To date, however, archaeological evidence has been limited to a scatter of small and apparently isolated shrines. Here, the authors combine airborne laser scanning with ground-based survey to define an extended urban network dating from the ninth century AD, which they identify as Mahendraparvata. This research yields new and important insights into the emergence of Angkorian urban areas.

Radiocarbon dates from recent excavations of a range of Angkorian Khmer (~9th–14th CE) stoneware kiln complexes provide a new and independent perspective on the timing and geography of Khmer ceramic production. These data demonstrate a clear two-phase sequence. The first, in the late 9th to late 12th centuries CE, marks a period of intensive production located both to the east of Angkor and to the south at Cheung Ek, south of Phnom Penh. A second shorter phase of production occurred in the late 13th to late 14th CE at more distant provincial settings following the collapse of the Angkorian state.

We report the chronological construction for the top portion of a speleothem, PC1, from southern Cambodia with the aim of reconstructing a continuous high-resolution climate record covering the fluorescence and decline of the medieval Khmer kingdom and its capital at Angkor (~9th–15th centuries AD). Earlier attempts to date PC1 by the standard U-Th method proved unsuccessful. We have therefore dated this speleothem using radiocarbon. Fifty carbonate samples along the growth axis of PC1 were collected for accelerator mass spectrometry (AMS) analysis. Chronological reconstruction for PC1 was achieved using two different approaches described by Hua et al. (2012a) and Lechleitner et al. (2016a). Excellent concordance between the two age-depth models indicates that the top ~47 mm of PC1 grew during the last millennium with a growth hiatus during ~1250–1650 AD, resulting from a large change in measured 14C values at 34.4–35.2 mm depth. The timing of the growth hiatus covers the period of decades-long droughts during the 14th–16th centuries AD indicated in regional climate records.

The impressive architecture of Angkor Wat conveys a sense of harmonious design, but recent survey using ground-penetrating radar (GPR), coupled with targeted excavation, reveals a more complex picture. Fragmentary traces of a quincunx of earlier towers have been detected, which were partially demolished when the outer enclosure and western gateway were completed. Are these the remains of a shrine used during the construction period? If so, they throw new light on associated ritual activity during the building of Angkor Wat.

Famous for its role as a Vishnuite temple during the twelfth and thirteenth centuries, Angkor Wat's subsequent fate has attracted less interest. Traces of modifications to the outer walls of the complex may, however, hold the key to understanding its role during its later phases. Here, holes in the masonry and structural changes to the substantial walls are investigated to demonstrate how wooden structures with a defensive role were built to protect the site sometime between the late thirteenth and early seventeenth centuries. The results reveal how Angkor Wat may have made its last attempt at defence.

In the tropical regions of southern Asia, Southeast Asia and the southern Maya lowlands, the management of water was crucial to the maintenance of political power and the distribution of communities in the landscape. Between the ninth and sixteenth centuries AD, however, this diverse range of medieval socio-political systems were destabilised by climatic change. Comparative study reveals that despite their diversity, the outcome for each society was the same: the breakdown of low-density urban centres in favour of compact communities in peripheral regions. The result of this, an ‘urban diaspora’, highlights the relationship between the control of water and power, but also reveals that the collapse of urban centres was a political phenomenon with society-wide repercussions.

Excavations at four Iron Age moated sites in the Mun Valley in Thailand have identified seminal innovations, defined as emergent properties, that illuminate the origins of the kingdom of Angkor. Combined with recent research at Angkor itself, they present a compelling case for re-examining fundamental cultural changes that took place over a period of little more than four centuries, from AD 400–800. They compare with similarly rapid developments in Mesoamerica and Mesopotamia; fundamental parallels are evident in the role of charismatic agents for change, an ideology conferring god-like status on leaders, a new and highly productive economic base, an expanded interaction sphere for the exchange of prestige goods, and endemic warfare.

Examination of skeletal material from graves at Phum Snay in north-west Cambodia revealed an exceptionally high number of injuries, especially to the head, likely to have been caused by interpersonal violence. The graves also contain a quantity of swords and other offensive weapons used in conflict. The authors propose a context for these warriors in the struggle between emergent polities in the Iron Age before the domination of Angkor.

Meticulous survey of the banks, channels and reservoirs at Angkor shows them to have been part of a large scale water management network instigated in the ninth century AD. Water collected from the hills was stored and could have been distributed for a wide variety of purposes including flood control, agriculture and ritual while a system of overflows and bypasses carried surplus water away to the lake, the Tonle Sap, to the south. The network had a history of numerous additions and modifications. Earlier channels both distributed and disposed of water. From the twelfth century onwards the large new channels primarily disposed of water to the lake. The authors here present and document the latest definitive map of the water network of Angkor.

Investigating the use of land during the medieval period at the celebrated ceremonial area of Angkor, the authors took a soil column over 2.5m deep from the inner moat of the Bakong temple. The dated pollen sequence showed that the temple moat was dug in the eighth century AD and that the agriculture of the immediate area subsequently flourished. In the tenth century AD agriculture declined and the moat became choked with water-plants. It was at this time, according to historical documents, that a new centre at Phnom Bakeng was founded by Yasovarman I.