"The Lydian era... is an era of which very little is known outside Sardis," explains Professor Greenewalt. Historical documents are limited, and archaeology plays a major role in illuminating Lydian culture. Only five to ten percent of the area occupied by Sardis, the capital of the Lydian empire and major cultural center, has been excavated thus far. As the team excavates through layers of the site, the top layers being the most recent, various structures are dated through the analysis of pottery, coins, and other artifacts. Experienced excavators try to develop a sense of confidence and resourcefulness among the inexperienced team members, allowing novices to work on their own, to learn from their mistakes, and to handle unexpected situations.