Sumer
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia, modern-day southern Iraq, during the Chalcolithic and Early Bronze ages, and one of the first civilizations in the world along with Ancient Egypt and the Indus Valley. Living along the valleys of the Tigris and Euphrates, Sumerian farmers were able to grow an abundance of grain and other crops, the surplus of which enabled them to settle in one place. Prehistoric proto-writing dates back before 3000 BC. The earliest texts, from c. 3300 BC, come from the cities of Uruk and Jemdet Nasr; early cuneiform script emerged around 3000 BC.
History of Bulgaria
The eneolithic Varna culture (5000 BC) represents the first civilization with a sophisticated social hierarchy in Europe. The centerpiece of this culture is the Varna Necropolis, discovered in the early 1970s. It serves as a tool in understanding how the earliest European societies functioned, principally through well-preserved ritual burials, pottery, and golden jewelry. The golden rings, bracelets and ceremonial weapons discovered in one of the graves were created between 4,600 and 4200 BC, which makes them the oldest gold artifacts yet discovered anywhere in the world. The Karanovo culture developed simultaneously with the one in Varna, and its earth layers serve as a stratigraphical gauge for the prehistory of the wider Balkans region.