Stoneware kilns in the Songkhram River basin
The Songkhram River drains the northern half of the Khorat plateau in Northeast Thailand, the region known as the Sakon Nakhon basin. The river's headwaters lie in Udon province, not far from the prehistoric site of Ban Chiang. Crossing the alluvial plains interrupted by occasional low hills, it flows sinuously eastward for 420 kilometers in a series of deep bends and oxbows over the flat terrain, cutting through the provinces of Nong Khai and Sakon Nakhon and entering the Mekong at Chaiburi in Nakhon Phanom province.
Kiln sites along the river were first recognized by Samruad Inban within Akat Amnuay district, Sakon Nakhon province (Samruad 1989). The sites were investigated by Louise Cort and Leedom Lefferts in 1989–90 and discussed with Amara Srisuchat in the Archaeology Division, Fine Arts Department of Thailand, and they were presented in conference papers (Cort 1991, Cort 1993, Cort and Lefferts 2000). Under Amara's direction, Archaeology Division staff surveyed the river sites and conducted an excavation in 1991–94. They identified sites along a ninety-kilometer stretch of the river, starting at the mouth (Anthropology Department, Archaeology Faculty, Silapakorn University 1996). The new finds were also reported in journals (Rakchonok 1993, Walailak 1996, Retka 1999; see Library). The wares were introduced in catalogues in Thailand (Pariwat et al 1996:77–79, 192–193) and Japan (Ozaki 1996, Tsuda 1999).
The survey identified more than ninety individual kilns, generally located at the mouths of streams flowing into the Songkhram. Density ranged from two or three kilns to twenty-eight in one cluster. Such sites represent the activities over time of men in nearby villages, collaborating in the use of one or two kilns at a time and replacing them after they were worn out by use or flooded by the river.
The repertory of the kilns seems to have been fairly consistent. The chief products were jars with narrow bodies and large funnel-shaped mouths making up a third of the vessel's height. Pairs of small ornaments sat on the shoulder close to the neck—small knobs, S-shaped ornaments made of clay coils, or similar shapes. Such jars were either unglazed (with a gray surface resulting from a smoky atmosphere in the kiln during firing) or glazed with a watery, caramel-brown glaze composed of wood ash and iron-bearing clay. The flat base bore dense parallel grooves left by dragging a twisted cord between the base and the wheelhead—with the wheel stopped rather than revolving—to separate the finished vessel. Such marks are diagnostic of the products of this region.
These jars were widely distributed in the Khorat plateau and bear a superficial resemblance to jars from various Lan Na kilns, but the bodies are narrower, the necks are taller, and the contours are less articulated. Many were used to bury cremated remains.
Another type of jar was made with a concentric double rim, the inner rim conical in shape and the outer rim everted. This jar was used specifically for fermenting and storing plaa dek, a mixture of river fish and salt that constitutes a major condiment and cooking ingredient in the local diet. When the jar was in use, the space between the inner and outer rim was kept filled with water, and a bowl-shaped lid was inverted rim-down into the water to create a seal that kept out insects and animals but permitted gas from the fermenting plaa dek to escape. Such jars are still made by the active kilns in the region and used in households. The market town of Si Songkhram is a center for household-based commercial production of plaa dek, using large jars made at local kilns.
Production of plaa dek was closely tied to the resources of fish in the river and salt and iron in the land. The Khorat plateau was an important center for processing salt from late prehistoric times. Salt-bearing earth (the product of salt domes left by an ancient sea bed) was scraped up and boiled with water. Iron resources were used to make the pans for boiling down the salt, which was traded widely. Production still continues at a village level, even though long-distance trade diminished after the fourteenth century with the arrival of cheap Chinese iron and the spread of saltmaking to other areas (Nitta 2006).
The repertory of the Songkhram River kilns also included a range of smaller vessels for household use, including small jars, basins, bowls, and pear-shaped bottles.