Sabaean Kingdom

To help the archaeologists study and date the archaeological silver coins excavated from burial soil, al-Ukhdoud castle, Najran, Saudi Arabia, it was necessary to reveal the impeded decorations and the inscriptions on these coins. For that it was necessary to remove the soiled deposits, encrustations, and corrosion layers covering these coins. To succeed in developing and establishing conservation processes for these coins, various tests were performed on the coins to assess their statement and condition. XRD analysis was used to characterize the coins. Also, scanning Electron Microscope (SEM) attached with energy-dispersive X-ray analyser (EDAX) was used to identify and analyse the corrosion products on the selected coins. Various selected cleaning processes that were suggested to remove the soiled deposits, encrustations, and corrosion layer covering these coins were tested. Mechanical cleaning, alkaline Rochelle salt, alkaline dithionite reduction technique, and electrolytic reduction techniques were tested. To evaluate the suggested cleaning processes used in this study, the coins before, while, and after the cleaning processes were investigated by various methods. SEM with EDAX and XRD techniques were used to characterize the coins before and after the final conservation. The results showed that the most adequate method that can be used safely and successfully for cleaning of the studied coins is as the following. In the beginning, the loosely corrosion layer on the coins has to be removed mechanically. Then, the coins should be treated with alkaline Rochelle salt technique. Finally, after finishing the treatments, the coins should be rinsed, dried, and isolated. The conservation processes used in this study can be applied effectively, safely, and successfully for cleaning and removing the soiled deposits, encrustations, and corrosion layers covering the coins in this treasure and the simulated archaeological coins. The archaeological and historical study of the decorations and inscriptions that appeared on the surface of the coins after their conservation process confirms that these coins belong to kingdoms of Qataban and Ḥimyar. The revealed decorations and inscriptions confirm that a part of the coins belong to Qataban kingdom which returns back to the first century BCE until the middle of the first century CE. The other part of the coins belongs to Ḥimyar kingdom which returns back to the first century BCE until the second century CE. The study confirms that the coins of this hoard date back to the period between last quarter of 1st century BCE-from the ruling time of the Ḥimyarite king, Shamnar Yuhan'im, to the end of the 2nd century CE-from the ruling time of the Himyarite king, Tha'ran Ya'ub. This study can be a guide for the con-servators who seek to cleaning processes for simulated coins. Also this study provides archaeologists and historians with very important materials that can help them interpret many questions, mysteries, missing information, a lot of historical facts, and secrets about the economic and technical developments during the ancient times in Najran city.

Yeha and the UNESCO world heritage site Aksum, both situated in the Ethiopian highlands, was the centre of the ancient kingdoms of Di’amat and Aksumite. The ruins of these kingdoms spread all over the Tigray
Plateau, show the wealth and influence of these civilisations. Both kingdoms achieved economic and political importance since there were focal points for the trade routes of ancient Egypt, South-Arabia and the Roman Empire to Africa and the Indian Ocean (D’Andrea et al. 2008: 152-154). Yeha is deemed to be the capital of Di’amat formed in the early first millennium BC (Gerlach 2014: 5-7). It shows a strong influence of Sabean culture, which might be connected to their dominance of the Red Sea region. However, the Ethio-Sabaean culture disappeared towards the mid-first millennium BC by unknown cause and was succeeded by the Aksumite kingdom. The area of Yeha has remained inhabited through the millenniums to present day and is today known for its ruins of the monumental structure Grat Be’al Gebri as well as the Great Temple.
The motivation of the geophysical survey was to obtain more information about the existence of surrounding settlement structures and their organisation. The selection of the different prospecting areas was predetermined by the accessibility and the requirement for areal magnetometer prospection. The total Earth’s magnetic field measurements and the subsequent interpretations are complicated by the shallow magnetic inclination of 15°.

The project is an Ethiopian-German cooperation project (ARCCH and TCTB ) and supported and financed by the DFG (DFG-Projekt Yeha).