The Amratian culture lasted from about 4000 to 3500 BC.[50] It is named after the site of El-Amra, about 120 km south of Badari. El-Amra is the first site where this culture group was found unmingled with the later Gerzean culture group, but this period is better attested at the Naqada site, so it also is referred to as the Naqada I culture.[51] Black-topped ware continues to appear, but white cross-line ware, a type of pottery which has been decorated with close parallel white lines being crossed by another set of close parallel white lines, is also found at this time. The Amratian period falls between S.D. 30 and 39 in Petrie's Sequence Dating system.[54]