Re-thinking the Emergence of Iron Metallurgy in Taiwan - a Trade Diaspora Model

Abstract

As a society is composed of waves of immigrants, overseas influences have been common to Taiwan since ancient times. Among these external forces, the overseas immigrant-influenced technological leap is believed to be the prime mover for Taiwan entering the Metal period (1800 BP) directly from the Neolithic period (5500-1800 BP). Several studies have proposed overseas influences, like foreign traders and craftspeople, for explaining the emergence of the Metal period and metallurgy in ancient Taiwan. In this doctoral research, I further apply the concept of trade diaspora and build a model to explore the introductory mechanism and localization process of foreign elements that led Taiwan from the Neolithic times into the Metal period. I hypothesize that these overseas materials, cultural elements, and metallurgy were brought by traders who were also metallurgical craftspeople in the form of trade diaspora. A three-stage trade diaspora model is proposed to accommodate the published data from the Jiuxianglan舊香蘭, Huakangshan花岡山, Shihsanhang十三行, and Chongde崇德sites for understanding the introductory mechanism and localization process of foreign elements. Ceramic, burial practice, and metallurgical tradition are the primary aspects for determining the existence of trade diasporic community in the proposed model. In addition to the published data, the newly excavated Blihun Hanben 漢本 (BHB) site is the primary fieldwork site and is expected to provide new data and insight into the proposed model. There are two major cultural layers (L4 1600-1000 cal. BP and L6 2000-1600 cal. BP) in the Blihun Hanben site. Totally, over 9000 kg ceramics, 2500 kg iron slag, 200 burials were unearthed during four years of salvage project. In this research, I applied technical typology to analyze ceramic and iron metallurgical remains. This concept reveals the embedded manufacturing stages from visible attributes on the end-product and helps us understand the choices made by the potter and smelter, and may further distinguish the hidden social boundaries between social groups. Instrumental analyses are applied to further support the technical typology. Ceramics are the most abundant remains in Taiwan's Neolithic and Metal periods context. Based on the technical typology, both L4 and L6 cultural layers have more than fifteen ceramic types, and I have designated those types into seven (L4) and seven (L6) wares. Petrographic analysis shows five sources for the temper for both L4 and L6 specimens. Those are BHB local, the southern part of the Ilan Plain, the northern part of the Ilan Plain, the Igneous/volcanic areas, and the East Rift Valley. It is reasonable to say that the BHB ceramic temper was acquired from locations ranging all over northern and eastern Taiwan. From a technical typological perspective, this petrographic analysis of temper provenience mainly consists with the macro analysis (by naked-eye) results, in other words, the ceramics in the same ceramic ware have the same temper provenience. The L4 ceramics match to known Shihsanhang cultural assemblage Pulowan subset, especially identical to the ceramic assemblage from the Chongde site. While L6 ceramics can hardly be matched with any known ceramic assemblage, L6 ceramics show a certain connection to the Upper Huakangshan ceramics. Multiple ceramic proveniences indicate the connectedness between the Blihun Hanben people and other eastern and northern Taiwan residents. Moreover, the ceramic analyses results fit the archaeological prediction of the proposed model. L4 unearthed over 99% of iron slag, and the heatmap of slag chronological distribution shows an abrupt increase of slag deposit from L6 to L4. This sudden increase of iron slag deposit indicates the practice of matured iron technology at the beginning of L4. Slag technical typology shows that bloomery was the metallurgical tradition of the BHB site, and the whole slag assemblage is dominated by smithing hearth bottom, which is the indicator of smithing activity. The lack of furnace body fragments also supports this result. Commonly speaking, a bloomery furnace is a onetime-use structure since the furnace needs to be broken for bloom extraction. Under this circumstance, a large number of furnace body fragments are usually associated with smelting slag in the smelting site. However, the examined BHB slag specimens lack both furnace-lining fragments and smelting slag; in contrast, this slag assemblage reflects intensive smithing activities (ironworking) rather than smelting (ironmaking). The micro-analyses (SEM-EDX) support the macro-analysis (technical typology). The specimens of the presumed smelting slag, which is rare in the whole slag assemblage, yielded typical iron smelting slag micro-structure and mineral composition. Long and semi-rectangular fayalite lath and dendritic wüstite are typical minerals in bloomery smelting slag. On the other hand, fat wüstite globules were found in the smithing hearth bottom specimens. Fat wüstite globule is the typical microstructure in smithing slag. While we did not find direct evidence of iron smelting, the large amount of smithing slag implied the frequent smelting practice near the Blihun Hanben site. The slag analyses result also fits the archaeological prediction of the proposed model. In summation, the possession of matured metallurgical ability is the crucial characteristic of trade diasporic craftspeople I proposed, and both the ceramic and metallurgical analyses support that the BHB L6 fit the second stage and BHB L4 fit the third stage of the proposed trade diaspora model. The proposed model represents a long-term adaptation of hypothetic trade diaspora communities to the local societies. While subsequent studies need to be carried out, the proposed model is not denied in the current research state.