As a consequence of the colonisation patterns the Völkerwanderung, the routes for trade and communication (chiefly the rivers), and of physical isolation (high mountains and deep forests) very different regional dialects developed. These dialects, sometimes mutually unintelligible, were used across the Holy Roman Empire.
As Germany was divided into many different states, the only force working for a unification or standardisation of German during a period of several hundred years was the general preference of writers trying to write in a way that could be understood in the largest possible area.
When Martin Luther translated the Bible (the New Testament in 1521 and the Old Testament in 1534) he based his translation mainly on this already developed language, which was the most widely understood language at this time. This language was based on Eastern Upper and Eastern Central German dialects and preserved much of the grammatical system of Middle High German (unlike the spoken German dialects in Central and Upper Germany that already at that time began to lose the genitive case and the preterit tense). In the beginning, copies of the Bible had a long list for each region, which translated words unknown in the region into the regional dialect. Roman Catholics rejected Luther's translation in the beginning and tried to create their own Catholic standard (Gemeines Deutsch) — which, however, only differed from 'Protestant German' in some minor details. It took until the middle of the 18th century to create a standard that was widely accepted, thus ending the period of Early New High German.
German used to be the language of commerce and government in the Habsburg Empire, which encompassed a large area of Central and Eastern Europe. Until the mid-19th century it was essentially the language of townspeople throughout most of the Empire. It indicated that the speaker was a merchant, an urbanite, not their nationality. Some cities, such as Prague (German: Prag) and Budapest (Buda, German: Ofen), were gradually Germanized in the years after their incorporation into the Habsburg domain. Others, such as Bratislava (German: Pressburg), were originally settled during the Habsburg period and were primarily German at that time. A few cities such as Milan (German: Mailand) remained primarily non-German. However, most cities were primarily German during this time, such as Prague, Budapest, Bratislava, Zagreb (German: Agram), and Ljubljana (German: Laibach), though they were surrounded by territory that spoke other languages.
Until about 1800, Standard German was almost only a written language. In this time, people in urban northern Germany, who spoke dialects very different from Standard German, learnt it almost like a foreign language and tried to pronounce it as close to the spelling as possible. Prescriptive pronunciation guides used to consider that northern German pronunciation to be the standard. However, the actual pronunciation of standard German varies from region to region.
Media and written works are almost all produced in standard German (often called Hochdeutsch in German), which is understood in all areas of German languages (except by pre-school children in areas which speak only dialect, for example Switzerland — but in this age of TV, even they now usually learn to understand Standard German before school age).
The first dictionary of the Brothers Grimm, the 16 parts of which were issued between 1852 and 1960, remains the most comprehensive guide to the words of the German language. In 1860, grammatical and orthographic rules first appeared in the Duden Handbook. In 1901, this was declared the standard definition of the German language. Official revisions of some of these rules were not issued until 1998, when the German spelling reform of 1996 was officially promulgated by governmental representatives of all German-speaking countries. Since the reform, German spelling has been in an eight-year transitional period where the reformed spelling is taught in most schools, while traditional and reformed spelling co-exist in the media. See German spelling reform of 1996 for an overview of the heated public debate concerning the reform.
During the 1870s, the German language successfully replaced Latin as the dominant language in all major European and North American universities, thanks to the prominence of German universities at the time. Most important research in the sciences for some decades afterward was published in German, and new universities preferred German instead of Greek or Latin mottoes (for example, Stanford University).