The researches we have just described, so far as they have been carried at present, show that many of the mounds of Susa, formed of an accumulation of débris and covered with a thin layer of sand deposited by the desert winds, were inhabited from prehistoric times to the Arab period. The prehistoric remains are found at a depth of over 80 feet, below the evidences of more advanced civilizations. After digging through the accumulated remains of forty centuries, the virgin soil is reached, and here are found worked flints, primitive pottery, and other objects similar to those found on all prehistoric sites. Above the level of the worked flints, and the rough, hand-made pottery, shaped without the aid of the wheel, another civilization is found, more advanced, although still prehistoric, which produced vases in sandstone and calcite of various sizes, and--far more important and fundamental--seals or stamps, proofs of a culture widely removed from barbarism. These seals are hemispherical in form, and pierced with a hole for suspension. The base or flat face is decorated with figures of animals engraved in rudimentary fashion by means of the drill and point. The most usual subject is a lion, or lion’s head. But nowhere at this level of the remains has the slightest trace of writing been found. The dwellings were huts, made either of beaten earth or of crude bricks. A thick layer of cinders and other unequivocal indications, enable us to assert that this primitive civilization disappeared owing to the massacre of the inhabitants and the burning of their dwellings. At this early period, to which it is impossible to assign even an approximate date, Susa suffered from some foreign invasion, and the pillagers installed themselves in place of the indigenous inhabitants, whom they destroyed. It is, therefore, a new civilization we find above the remains of the prehistoric people, and which introduces us to the domain of actual history, the commencement of the Elam-Anzanite period. It is to this invading race that Susa owes her first written documents. These inscriptions, although they are in a language almost unknown to us, are undoubtedly the most important that this period has hitherto yielded. The earliest text known is engraved on a bone cylinder (fig. 242). The mere appearance of the signs strikes us with the remote antiquity to which they must be assigned; they are actually hieroglyphs. Among them apparently there can be distinguished an insect, a double comb, a quadruped, a bird, some grains of wheat, and a man carrying a double load on his shoulders. On the lower part of the cylinder two bulls are depicted, each with his head over a manger. [Illustration: Fig. 242.--Bone cylinder, showing the earliest stage of cuneiform writing (Louvre).]