Very few carpets still exist today which represent the transition between the late Seljuq and early Ottoman period. A traditional Chinese motif, the fight between phoenix and dragon, is seen in an Anatolian rug, today at the Pergamon Museum, Berlin. Radiocarbon dating confirmed that the "Dragon and Phoenix" carpet was woven in the mid 15th century, during the early Ottoman Empire. It is knotted with symmetric knots. The Chinese motif was probably introduced into Islamic art by the Mongols during the thirteenth century. Another carpet showing two medallions with two birds besides a tree was found in the Swedish church of Marby. More fragments were found in Fostat, today a suburb of the city of Cairo. A carpet with serial bird-and-tree medallions is shown in Sano di Pietro's painting "Marriage of the Virgin" (1448–52).