Also a large number of elaborately crafted gold and silver treasure sets from the 5th and 4th century BC were unearthed. In the following decades, those were exhibited in museums around the world, thus calling attention to ancient Thracian culture. Since the year 2000, Bulgarian archaeologist Georgi Kitov has made discoveries in Central Bulgaria, in an area now known as The Valley of the Thracian Kings. The residence of the Odrysian kings was found in Starosel in the Sredna Gora mountains. A 1922 Bulgarian study claimed that there were at least 6,269 necropolises in Bulgaria.