In any case, it is certain that a very long period of purely Accadian civilization must have existed prior to the introduction of Semitic influences, and long before the foundation of a Semitic dynasty by Sargon I. With these facts it will no longer seem surprising that some high authorities assign as early a date as 6000 B.C. for the dawn of Chaldæan civilization, and consider that it may be quite as old or even older than that of Egypt. The great antiquity assigned to these dates from books and monuments is confirmed by other deductions. The city of Eridhu, which was generally considered to be the oldest in Chaldæa, and was the sanctuary of the principal god, Eâ, appears to have been a sea-port in those early days, situated where the Euphrates flowed into the Persian Gulf. The ruins now stand far inland, and Sayce computes that about 6000 years must have elapsed since the sea reached up to them. Astronomy affords a still more definite confirmation. The earliest records and traditions show that before the commencement of any historic period the year had been divided into twelve months, the course of the sun mapped out among the stars, and a zodiac established of the twelve constellations, which has continued in use to the present day. The year began with the vernal equinox, and the first month was named after the "propitious Bull," whose figure constantly appears on the monuments as opening the year. The sun, therefore, was in Taurus at the vernal equinox when this calendar was formed, which could only be after long centuries of astronomical observation; but it has been in Aries since about 2500 B.C., and first entered in Taurus about 4700 B.C. Records of eclipses were also kept in the time of Sargon I., which imply a long preceding period of accurate observation; and the Ziggurat, or temple observatory, built up in successive stages above the alluvial plain, which gave rise to the legend of the Tower of Babel, is found in connection with the earliest temples. The diorite statues also and engraved gems found at Sirgalla testify to a thorough knowledge of the arts of metallurgy at this remote period, and to a commercial intercourse with foreign countries from which the copper and tin must have been derived for making bronze tools capable of cutting such hard materials. The existence of such a commercial intercourse in remote times is confirmed by the example of Egypt, where bronze implements must have been in use long before the date of Menes; and although copper might have been obtained from Sinai or Cyprus, tin or bronze must have been imported from distant foreign countries alike in Egypt and in Chaldæa.