Potsherds (pottery shards) are the most abundant archaeological artifacts at Nok sites. Since 2009, excavated pottery has been undergoing systematic analysis with a central aim to try and establish a chronology. Certain attributes of the pottery such as decoration, shape, and size appear with an increasing frequency and then disappear, being replaced with different pottery attributes. This change can sometimes allow one to divide the progression into different intervals based on the different attributes. In total approximately 90,000 potsherds have been collected, of which 15,000 have been considered diagnostic, meaning that they are decorated, sherds from the rim or the bottom of the vessel, or they have handles or holes in them. The results of the pottery analysis can be delineated into three distinct time periods: Early, Middle, and Late.