Horoscopic astrology is a system that some claim to have developed in the Mediterranean region and specifically Hellenistic Egypt around the late 2nd or early 1st century BC. However, horoscopic astrology has been practiced in India since ancient times, and Vedic astrology is the oldest surviving form of horoscopic astrology in the world.The tradition deals with two-dimensional diagrams of the heavens, or horoscopes, created for specific moments in time. The diagram is then used to interpret the inherent meaning underlying the alignment of celestial bodies at that moment based on a specific set of rules and guidelines. A horoscope was calculated normally for the moment of an individual's birth, or at the beginning of an enterprise or event, because the alignments of the heavens at that moment were thought to determine the nature of the subject in question. One of the defining characteristics of this form of astrology that makes it distinct from other traditions is the computation of the degree of the Eastern horizon rising against the backdrop of the ecliptic at the specific moment under examination, otherwise known as the ascendant. Horoscopic astrology is the most influential and widespread form of astrology in Africa, India, Europe and the Middle East. Medieval and most modern Western traditions of astrology have Hellenistic origins.Central to horoscopic astrology and its branches is the calculation of the horoscope or astrological chart. This two-dimensional diagrammatic representation shows the celestial bodies' apparent positions in the heavens from the vantage of a location on Earth at a given time and place. The horoscope is also divided into twelve different celestial houses which govern different areas of life. Calculations performed in casting a horoscope involve arithmetic and simple geometry which serve to locate the apparent position of heavenly bodies on desired dates and times based on astronomical tables. In ancient Hellenistic astrology the ascendant demarcated the first celestial house of a horoscope. The word for the ascendant in Greek was ὡροσκόπος (hōroskopos) from which horoscope derives. In modern times, the word has come to refer to the astrological chart as a whole.