Medieval tomb-stones which can be found in the Zagora area (during the Middle Ages this is the part of Croatia between Klis, Trogir, Šibenik and Drniš) are the most impressive manifestations of an indigenous Croatian folk art. In addition to their sometime impressive dimensions, our attention is even more drawn by the ornaments decorated in relief on the monuments. In addition to numerous recognizable motifs, enigmatic figural compositions on four tomb-stones from Bisko, Dugopolje, Konjsko and Mirlović Zagora stand out and ought to be emphasized. They show aurora borealis or the polar light. Just as it is the case today in ages past this spectacular phenomenon could likewise not pass unrecorded. Medieval manuscripts bear witness to this as do these, contemporary figural representations. In keeping with internationally accepted standardized terms, we see that in Bisko we have a modified arch in the shape of a leaning letter “T”; in Dugopolje two curtains are recorded in the shape of the letter “H”; in Konjsko we have the image of a modified arch while in Mirlović Zagora there are two curtains similar to the letter “C” and an arch in the shape of an upturned letter “T”. Since the half moon is an integral part of each composition, we can with certainty establish that the whole presentation evokes the actual appearance of the heavens at the moment the deceased had passed away. It was precisely because of its rare appearance that polar light served as a good reminder to the family of the deceased and this was the reason why it had it immortalized on the tomb-stones. However, we find it difficult to date them more precisely within the period between 1350 to 1463 which can be considered the high point of their development.