In ancient Mesopotamia, Nirah, the messenger god of Ištaran, was represented as a serpent on "kudurrus", or boundary stones. Representations of two intertwined serpents are common in Sumerian art and Neo-Sumerian artwork and still appear sporadically on cylinder seals and amulets until as late as the thirteenth century BC. The horned viper ("Cerastes cerastes") appears in Kassite and Neo-Assyrian kudurrus and is invoked in Assyrian texts as a magical protective entity. A dragon-like creature with horns, the body and neck of a snake, the forelegs of a lion, and the hind-legs of a bird appears in Mesopotamian art from the Akkadian Period until the Hellenistic Period (323 BC–31 BC). This creature, known in Akkadian as the "mušḫuššu", meaning "furious serpent", was used as a symbol for particular deities and also as a general protective emblem. It seems to have originally been the attendant of the Underworld god Ninazu, but later became the attendant to the Hurrian storm-god Tishpak, as well as, later, Ninazu's son Ningishzida, the Babylonian national god Marduk, the scribal god Nabu, and the Assyrian national god Ashur.