He is commonly designated as "En-zu", which means "lord of wisdom". During the period (c. 2600–2400 BC) that Ur exercised a large measure of supremacy over the Euphrates valley, Sin was naturally regarded as the head of the pantheon . It is to this period that we must trace such designations of Sin as "father of the gods" , "chief of the gods" , "creator of all things" , and the like. The "wisdom" personified by the moon-god is likewise an expression of the science of astronomy or the practice of astrology, in which the observation of the moon's phases is an important factor.