Archaeological finds have led to the assumption that the Indo-European language, from which almost all European languages have developed, can be traced back to the Kurgan culture. The Kurgan's early Germanic language is also referred to as Proto-Indo-European. At that time, the Germanic language was already separating itself from other languages, a process that would continue until the beginning of the Common Era. Around this time, a difference could already be observed between the Scandinavian or North Germanic languages and the West Germanic language of the Germans living in Western Europe. From that point onwards, West Germanic, to which Limburgish belongs, began to evolve into several separate languages.

West Germanic branched out into three different linguistic groups. The region consisting of the northern Lower Countries was inhabited by the Ingvaeones or North Sea Germans, who lived along the North Sea coast, and included Frisians, Anglons and Saxons, amongst others. A second group, located in the southern Low Countries and northern France, and which therefore included the predecessors of Limburgers, were known as Istvaeones or Rhine Weser Germans. A third group consisted of the Herminones, or Elbe Germans, which included the Alemanni and Bavarians in the southern and southwestern parts of present-day Germany. This early division of West Germanic into three linguistic groups eventually led to various separate languages, such as Old English (Anglo-Saxon), Old Frisian, Old Saxon (Old Low German), Old High German, Old Dutch (Old Low West Franconian) and Old Limburgish (Old Low East Franconian).

The second Germanic or High German consonant shift originated in the South German Alps in the 4th or 5th century CE. This sound change in the language extended towards the north, gradually losing strength along the way. The outcome was the differences between High and Low German. The Ripuarian dialect, to which the dialects of Kerkrade and Vaals belong, were fully exposed to this consonant shift, Limburgish only partially, and other forms of Germanic in the Lower Countries not at all. Following this consonant shift, English and High German can more easily be distinguished as separate languages. However, similar classification of Frisian, Dutch, Lower German and Limburgish proves more difficult, since all of these form part of the West Germanic language group, and have intermingled and influenced one another over time.

In the 4th and 5th centuries, the language used in the Low Countries varied from region to region. Insofar as their language was concerned, the southern Low Countries had been subject to a strong Roman influence and were ‘Germanised’ much later than the northern Low Countries. Moreover, the coastal dialects of West Germanic, from West Flanders to Denmark, were more exposed to a Saxon influence and are therefore sometimes also referred to as Ingvaeonic. The population on the Dutch coast was most probably also of Saxon and Frisian origin. By contrast, in all likelihood the language spoken in the Limburgish region at the time would not have been subject to any Ingvaeonic influence.

Another significant event in this era is the deep impact Latin must have had on the language of the Germanic peoples who lived under Roman rule. Many words in the Germanic languages, and consequently Limburgish, were derived from Latin in those days. Other contributing factors are likely to have included trade contacts and the enlistment of our predecessors in the Roman army.

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http://www.dbnl.org/tekst/vooy001gesc01_01/vooy001gesc01_01_0003.htm, 20 (17-01-2008).