The field work from 5 March – 17 April 2011 included:
The possible centre of the reign of Ādityavarman is on Bukit Gombak, a large mound south of Batusangkar. Bukit Gombak lies in the middle of the fertile plain of the valley of Tanah Datar (“flat land”), south of the volcano Gunung Merapi along the Sungai Selo, a tributary of the Indragiri River which drains to the East coast of Sumatra. Here the oldest Ādityavarman-inscription in the highland of Sumatra dating to the year 1356 was found. It mentions the existence of a palace, the erection of a cloister and temple buildings.
At the plateau of Bukit Gombak and at the adjacent smaller hilltop of Bukit Kincir, ten areas were excavated, totaling 1078m2. The locally made earthenware and other artefacts including stone and metal objects, glass beads, Chinese ceramics of the Sung and early Ming Dynasty, as well as imported ceramics from the Southeast Asian mainland, point to a residential occupation of the site at least between the 14th and 16th centuries. From a total of 15,000 sherds, which were mainly collected at the execution trenches B, C and D, 1197 diagnostic sherds were filed. In three trenches numerous postholes were unearthed. At the most eastern trench E, 18 aligned postholes became visible which form the southwestern corner of a dwelling of considerable size. At the western slope of Bukit Gombak an ancient water source was discovered in an artificially terraced wall of rock. Two test pits G and H at the nearby Bukit Kincir revealed stone alignments which were assigned to potential grave sites.
Two methods were used to detect potential subsurface features of archaeological interest: gradient magnetometry (magnetometry) and ground penetrating radar. The radar was tested in the surface strata of three excavation trenches (totaling 243 m2). The survey with the magnetometer covered a total 9300 m2 of the site and recorded both archaeological features and anomalies created by recent disturbances.
Megalithic remains were mapped in three valleys of the Minangkabau region of West Sumatra: the Mahat and Sinamar valleys and in the Tanah Datar. They either form clusters of up to 400 stones or they are upright standing single monuments. Some are decorated, some are rounded and shaped as swords (kris-shape) from 1-4 m in height. In Tanah Datar megalithic remains represent either grave markers for burials or point to communal meeting sites.
The aim of the philological part of the Tanah Datar Project is to study and publish a complete corpus of the inscriptions issued by Ādityavarman. Rubbings were made. Prof. Arlo Griffiths is editing the inscriptions to deliver a sound basis by providing critical editions of all the relevant documents with annotated translations, good images that allow verification of the readings, and relatively elaborate explanations of the language and contents of the inscriptions.