There is even evidence of the Egyptians burying themselves with grave goods very early in their prehistory. Examples of these grave goods included pots, combs, stone vessels, and slate palettes. Beads made of basalt deposited in graves in the Fertile Crescent date to the end of the Upper Paleolithic, beginning in about the 12th to 11th millennium BC. The distribution of grave goods are a potential indicator of the social stratification of a society. Thus, early Neolithic graves tend to show equal distribution of goods, suggesting a more or less classless society, while in Chalcolithic and Bronze Age burials, rich grave goods are concentrated in "chieftain" graves (barrows), indicating social stratification. It is also possible that burial goods indicate a level of concern and consciousness in regard to an afterlife and related sense of spirituality. For example, when they buried pharaohs in ancient Egypt, they buried common house hold items, food, vehicles, etc. so they could have a comfortable afterlife. Famous grave sites The expression of social status in rich graves is taken to extremes in the royal graves of the Bronze Age. In the Theban Necropolis in Ancient Egypt, the pyramids and the royal graves in the Valley of the Kings are among the most elaborate burials in human history. This trend is continued into the Iron Age. An example of an extremely rich royal grave of the Iron Age is the Terracotta Army of Qin Shi Huang. In the sphere of the Roman Empire, early Christian graves lack grave goods, and grave goods tend to disappear with the decline of Greco-Roman polytheism in the 5th and 6th centuries. Similarly, the presence of grave goods in the Early Middle Ages in Europe has often been taken as evidence of paganism, although during the period of conversion in Anglo-Saxon England and the Frankish Empire (7th century), the situation may be more complicated. In the Christian Middle Ages, high-status graves are marked on the exterior, with tomb effigies or expensive tomb stones and still had certain grave goods such as accessories and textiles. The practice of placing grave goods with the dead body has thus an uninterrupted history beginning in the Upper Paleolithic, if not the Middle Paleolithic. Many people would assume that the introduction of Christianity led to the absence of grave goods, however, there were many different Christian tombs that were shown to still have grave goods such as