An archeology team discovered a set of stone tombs dating back to prehistoric times in the cross-border region of Pileh-Chai in the north of Namin, a city in Ardebil Province. In addition to the tombs, some tools made of obsidian have been discovered in the region, IRNA quoted Mohammad Alizadeh Soula, the team leader, as saying on Thursday. Obsidian is a volcanic glass used in the past in cutting and piercing tools. Archeological studies in Namin were launched Nov. 5 with the aim of preparing the archeological map of the city. The first phase of studies, which focuses on the northern half of the city covering 5,000 hectares and including 40 villages, is now underway. According to the Ardebil chapter of the Iran Cultural Heritage, Handicrafts and Tourism Organization, the last archeological activities in the region go back to late 19th century when French archeologist Jacques de Morgan conducted research. Namin is located 30 kilometers east of Ardebil of Ardebil-Gilan roadway.