Archaeological research in Thailand was established half a century ago and since then has made great strides in contributing to our understanding of the region's prehistory (e.g., Bayard 1980a, 1980b; Glover 1990; Gorman and Charoenwongsa 1976; Higham 1989; Higham and Kijngam 1984; Sorensen and Hatting 1967). In the past three decades, applications of most current frameworks and methodologies (e.g., studies of gender and social identities; economic production and exchange networks; and land uses and settlement patterns) (Bacus 2006; Bellina and Glover 2004; Boyd 2008; Ho 1992; Mudar 1995; Penny 1984; Theunissen et al. 2000; Vincent 2004; Welch 1985) have led to a growing awareness of regional variability and chronological distinctions between technological and sociocultural developments of the bronze and iron ages (Eyre 2006; Natapintu 2007; White and Hamilton 2009; White and Pigott 1996).
In the discussion to follow, the period of primary focus is the "Metal Age," the prehistoric period during which the metal technologies of bronze and later iron appeared in the region. In Thailand, the Metal Age precedes the appearance of protohistoric states and follows a period of unknown length, here termed "pre-Metal Age," when villages and plant cultivation developed along with ceramic and polished stone tool technologies. Despite attempts to argue that these technological transitions coincided with major social hierarchical transformations (Higham 1996:316, 2002:224-227, 2004:53-55; O'Reilly 2007:5, 2008:386), there does not appear to have been any overt, concomitant change in terms of sociopolitical elements of the kind that closely coincided with the appearance and development of metal technology in some parts of the Old World such as Mesopotamia and the central plain of China (e.g., Childe 1944; Heskel 1983; Muhly 1988).
Regardless of continuing debates surrounding Thailand's Metal Age chronological range and the role of metal technology, the Metal Age communities in Thailand underwent two major technological transitions and can be divided into two major periods: bronze age (c. 2000-600 B.C.) and iron age (c. 600 B.C.-A.D. 500) (Bacus 2006; Bronson and White 1992; White 2008; White and Hamilton 2009; cf. Higham and Higham 2008; Pigott and Ciarla 2007; Rispoli 2007). The use of the terms "bronze age" and "iron age" is intended to emphasize a technological sequence that existed irrespective of chronological controversies (Bacus 2006) or sociopolitical organization (White 2002).
It is argued here that the prevailing model of hierarchical sociopolitical organization, existing exclusively during the Metal Age and protohistoric period, is overly generalized. An alternative approach that incorporates underlying indispensable circumstances such as social variability and regional landscape is proposed to enrich our understanding of the development of social complexity in the region. The goal of this article is to explore a heterarchy framework that can be equally tested along with a hierarchical model. We summarize a recent intensive survey in central Thailand that encompasses several adjacent environmental zones and documents economic changes and shifting social networks over time. It is hoped that this investigation will generate debate and spur future investigations.
Social Complexity in Metal Age Thailand
Developments of social complexity may have first emerged in northeast Thailand during the bronze age, as evidenced by variations of mortuary wealth and treatment at intra- and inter-site levels (O'Reilly 2003; Talbot 2007). Nevertheless, the characteristics are difficult to categorize or generalize beyond individual sites to a regional scale. Mortuary evidence at the sites of Ban Chiang, Ban Na Di, and Ban Lum Khao show subtle representation of marked status differentials supporting the interpretation that such communities could be characterized as small autonomous villages (Higham 2004; O'Reilly 2003; White 1995). …