In 525 BCE, Egypt was conquered by the Persians. The 1st century BCE Egyptian Dendera Zodiac shares two signs – the Balance and the Scorpion – with Mesopotamian astrology.[35]nnWith the occupation by Alexander the Great in 332 BCE, Egypt became Hellenistic. The city of Alexandria was founded by Alexander after the conquest, becoming the place where Babylonian astrology was mixed with Egyptian Decanic astrology to create Horoscopic astrology. This contained the Babylonian zodiac with its system of planetary exaltations, the triplicities of the signs and the importance of eclipses. It used the Egyptian concept of dividing the zodiac into thirty-six decans of ten degrees each, with an emphasis on the rising decan, and the Greek system of planetary Gods, sign rulership and four elements.[36] 2nd century BCE texts predict positions of planets in zodiac signs at the time of the rising of certain decans, particularly Sothis.[37] The astrologer and astronomer Ptolemy lived in Alexandria. Ptolemy's work the Tetrabiblos formed the basis of Western astrology, and, "...enjoyed almost the authority of a Bible among the astrological writers of a thousand years or more