Any method used to order time and to place events in the sequence in which they occurred. A sequential ordering that places cultural entities in temporal, and often spatial, distribution. It involves the collection of dates or successive datings establishing the position in time of a series of phenomena such as the phases of a civilization or the events of the history of a state. A chronology is relative/floating when only the order of a succession of facts is known, but not their dates, and absolute when the opposite is true. For periods or areas for which no textual evidence is available, relative chronologies have to be established and these are mostly based on pottery sequences and typology. Relative chronology is also based on the application of the principles of stratigraphy and cross-dating. The discovery of inscribed monuments and calendars associated with dated astronomical observations contributed to the development of an Egyptian chronology and it has served as a framework - through cross-dating - for all other Near Eastern chronologies. Inscribed Egyptian objects found in Near Eastern contexts have allowed the latter to be dated. Absolute chronology is based on scientific methods such as radiocarbon dating, thermoluminescence dating, and archaeomagnetism. Dates are often calibrated with dendrochronological dates. For dates after 1500 BC, an absolute chronology is not likely to change by more than ten years.