When trade between China and Southeast Asia blossomed between the eleventh and fourteenth centuries, Chinese traders began to form overseas Chinese communities. Their presence had significant effects on the region, including the formation of new urban settlements and the introduction of new lifestyles in which imported items played an important part, not only among the elite, but among many hinterland groups who probably never saw a Chinese trader but rapidly integrated Chinese products into their displays of status.
Chinese commercial guides from the thirteenth and fourteenth centuries give detailed lists of the items which were in demand at various Southeast Asian ports. These include perishable items such as cloth, and more durable items including metal, ceramics and glass, which archaeologists can hope to find and thereby to reconstruct the interplay between economic activity and social change during this period.
Extensive studies have been devoted to the appreciation and study of Chinese porcelain found in Southeast Asian sites. The distribution and styles of Chinese glass in Southeast Asia during this period is in contrast almost completely unknown.
The neglect of this material is not commensurate with its potential to illuminate the economic and social situation. While it is true that glass artifacts have a narrower range of uses than ceramics, glass beads were commonly mentioned in Chinese descriptions of trade goods in demand in Southeast Asia. Ethnographic accounts of Southeast Asian material culture devote considerable attention to the use of beads in a variety of contexts.
Several problems have inhibited archaeologists from exploiting the potential of glass beads to illuminate trading patterns. These include difficulty in obtaining samples with reliable provenances, and doubt over the reliability of classification schemes based only on visual characteristics. Study of the classification and distribution of beads can do much to delineate the characteristics of trade networks in Southeast Asia.
Glass artifacts excavated from a fourteenth-century site (Fort Canning, Singapore) have been analyzed using the energy-dispersive X-ray fluorescence (EDXRF) technique at the Physics Laboratory, National University of Singapore.(1) In the first experiment, analysis of sherds from twenty-four glass vessels and five groups of beads shows that the glass can be divided into three groups based on elemental composition. Thus fourteenth-century Singapore obtained its glass from three different sources.
The objects analyzed were of different sizes and shapes, making it difficult to obtain data on the absolute concentrations of trace elements in the glass. This problem can be solved by measuring the relative concentrations of elements instead. This semi-quantitative method is equally useful, and in some cases is more reliable than the quantitative method which is conventionally applied.(2) In fact, principal component analysis which we use requires the data to be auto-scaled to have zero mean and unit variance. Therefore absolute values are not required for such analysis. The EDXRF technique is non-destructive. Thus the same samples can be tested repeatedly and the results can be reverified, a clear advantage compared to the destructive technique normally used.
The three groups of glass identified in the first experiment are internally quite homogeneous and easily distinguished from one another, which gives considerable confidence that the results have succeeded in identifying real groups and do not result from sampling or other bias. Group One consisted of only one artifact: a four-colour bangle which is quite different in composition as well as appearance from all other artifacts analyzed. It is characterized by high concentrations of lead, zinc, barium and tin. Both by composition and appearance it can be identified as of Indian origin, and dating from the thirteenth or fourteenth century. …