Periodization
Periodization is the process or study of categorizing the past into discrete, quantified named blocks of time. This is usually done in order to facilitate the study and analysis of history, understanding current and historical processes, and causality that might have linked those events. This results in descriptive abstractions that provide convenient terms for periods of time with relatively stable characteristics. However, determining the precise beginning and ending to any ‘period’ is often arbitrary, since it has changed over time over the course of history. To the extent that history is continuous and not generalized, all systems of periodization  are more or less arbitrary. Yet without named periods, however clumsy or imprecise, past time would be nothing more than scattered events without a framework to help us understand them. Nations, cultures, families, and even individuals, each with their different remembered histories, are constantly engaged in imposing overlapping schemes of temporal periodization. Periodizing labels are continually challenged and redefined, but once established, a period "brand" is so convenient that many are hard to change or shake off. History. The division of history into ages or periods is very old, and recorded practically as early as the first development of writing . The "Sumerian King List", dating to the second millennium BC and for most parts not considered historically accurate, operates with dynastic regnal eras. The classical division into a Golden Age, Silver Age, Bronze Age, Heroic Age and Iron Age goes back to Hesiod. One Biblical periodization scheme commonly used in the Middle Ages was Saint Paul's theological division of history into three ages: the first before the age of Moses (under nature); the second under Mosaic law (under law); the third in the age of Christ (under grace). But perhaps the most widely discussed periodization scheme of the Middle  Ages was the Six Ages of the World, where every age was a thousand years counting from Adam to the present, with the present time (in the Middle Ages) being the sixth and final stage. Background. Not only do periodizing blocks inevitably overlap, they often seemingly conflict with or contradict one another. Some have a cultural usage (the "Gilded Age"), others refer to prominent historical events (‘the Inter-War years: 1918–1939’), yet others are defined by decimal numbering systems (‘the 1960s’, ‘the 17th century’). Other periods are named from influential or talismanic individuals (the ‘Victorian Era’, the ‘Edwardian Era’, the  ‘Napoleonic Era’). Some of these usages will also be geographically specific. This is especially true of periodizing labels derived from individuals or ruling dynasties, such as the Jacksonian Era in America, the Meiji Era in Japan, or the Merovingian Period in France. Cultural terms may also have a limited reach. Thus the concept of the "Romantic period" is largely meaningless outside the Western world of Europe and European-influenced cultures. Likewise, ‘the 1960s’, though technically applicable to anywhere in the world according to Common Era numbering, has a certain set of specific cultural connotations in certain countries. For this reason  it may be possible to say such things as “The 1960s never occurred in Spain”. This would mean that the sexual revolution, counterculture, youth rebellion and so on never developed during that decade in Spain's conservative Roman Catholic culture and under Francisco Franco's authoritarian regime. Likewise it is very often said, as the historian Arthur Marwick has, that ‘the 1960s’ began in the late 1950s and ended in the early 1970s. His reason for saying this is that the cultural and economic conditions that define the meaning of the period covers more than the accidental fact of a  10-year block beginning with the number 6. This extended usage is termed the ‘long 1960s’. This usage derives from other historians who have adopted labels such as “the long 19th century” (1789–1914) to reconcile arbitrary decimal chronology with meaningful cultural and social phases. Similarly, an Eighteenth Century may run 1714–1789. Eric Hobsbawm has also argued for what he calls “the short twentieth century”, encompassing the period from the First World War through to the end of the Cold War. Similar problems attend other labels. Is it possible to use the term ‘Victorian’ outside Britain, and even within, does her  reign of 1837–1901 usefully constitute a historical period? It sometimes is used when it is thought that its connotations usefully describe the politics, culture and economic conditions characteristic of the last two-thirds of the nineteenth century. Nevertheless, periodizing terms often have negative or positive connotations that may affect their usage. This includes "Victorian", which often negatively suggests sexual repression and class conflict. Other labels such as "Renaissance" have strongly positive characteristics. As a result, these terms sometimes extend in meaning. Thus the "English Renaissance" is often used for a period largely identical to the "Elizabethan Period" or reign of  Elizabeth I, and begins some 200 years later than the Italian Renaissance. However the "Carolingian Renaissance" is said to have occurred during the reign of the Frankish king Charlemagne, and his immediate successors. Other examples, neither of which constituted a "rebirth" in the sense of revival, are the "American Renaissance" of the 1820s–60s, referring mainly to literature, and the "Harlem Renaissance" of the 1920s, referring mainly to literature but also to music and the visual arts. The conception of a ‘rebirth’ of Classical Latin learning is first credited to the Italian poet Petrarch (1304–1374), the father of Renaissance Humanism, but  the conception of a rebirth has been in common use since Petrarch's time. The dominant usage of the word "Renaissance" refers to the cultural changes that occurred in Italy that culminated in the High Renaissance around 1500–1530. This concept applies dominantly to the visual arts, and the work of Michelangelo, Raphael, and Leonardo da Vinci. Secondarily it is applied to other arts, but it is questionable whether it is useful to describe a phase in economic, social and political history. Many professional historians now refer to the historical periods commonly known as the Renaissance and the Reformation as the  start of the Early Modern Period, which extends much later. There is a gradual change in the courses taught and books published to correspond to the change in period nomenclature, which in part reflects differences between social history and cultural history. The new nomenclature suggests a broader geographical coverage and a growing attention to the relationships between Europe and the wider world. The term Middle Ages also derives from Petrarch. He was comparing his own period to the Ancient or Classical world, seeing his time as a time of rebirth after a dark intermediate period, the Middle Ages. The idea  that the Middle Ages was a middle phase between two other large scale periodizing concepts, Ancient and Modern, still persists. It can be sub-divided into the Early, High and Late Middle Ages. The term Dark Ages is no longer in common use among modern scholars because of the difficulty of using it neutrally, though some writers have attempted to retain it and divest it of its negative connotations. The term "Middle Ages" and especially the adjective "medieval" can also have a negative ring in colloquial use ("the barbaric treatment of prisoners in such-and-such a prison is almost  medieval") but this does not carry over into academic terminology. However, other terms, such as Gothic architecture, used to refer to a style typical of the High Middle Ages have largely lost the negative connotations they initially had, acquiring new meanings over time (see Gothic architecture and Goth subculture). The Gothic and the Baroque were both named during subsequent stylistic periods when the preceding style was unpopular. The word "Gothic" was applied as a pejorative term to all things Northern European and, hence, barbarian, probably first by Giorgio Vasari. Vasari is also credited with first using the term "Renaissance" ("rinascita ) to describe the period during which he was art historian, artist, and architect. Giorgio Vasari coined the term Gothic" in an effort to describe, particularly architecture, that he found objectionable, supposedly saying "it is as if the Goths built it". The word "baroque"—derived from similar words in Portuguese, Spanish, or French—literally refers to an irregular or misshapen pearl. Its first use outside the field of jewellery manufacture was in the early 18th century, as a criticism of music that was viewed as over-complicated and rough. Later, the term was also used to describe architecture and art. The Baroque  period was first designated as such in the 19th century, and is generally considered to have begun around 1600 in all media. Music history places the end of the period in the year 1750 with the death of J. S. Bach, while art historians consider the main period to have ended significantly earlier in most areas. Three-age system. The usual method for periodization of the distant prehistoric past, in archeology is to rely on changes in material culture and technology, such as the Stone Age, Bronze Age and Iron Age and their sub-divisions also based on different styles  of material remains. Despite the development over recent decades of the ability through radiocarbon dating and other scientific methods to give actual dates for many sites or artefacts, these long-established schemes seem likely to remain in use. In many cases neighbouring cultures with writing have left some history of cultures without it, which may be used. Historiography. Some events or short periods of change have such a drastic effect on the cultures they affect that they form a natural break in history. These are often marked by the widespread use of both "pre-" and "post-" phrases centred on the  event, as in "pre-Reformation" and "post-Reformation", or "pre-colonial" and "post-colonial". Both pre-war and post-war are still understood to refer to World War II, though at some future point the phrases will need to be altered to make that clear. World history. Several major periods historians may use are Although "post-classical" is synonymous with the Middle Ages of Western Europe, the term "post-classical" is not necessarily a member of the traditional tripartite periodization of Western European history into ‘classical’, ‘middle’ and ‘modern’.