Originally the language of the gnomes called "Gamoltunge" (old/ancient tongue), the Northern Trade language evolved into the modern variant we have today. It is strongly mixed with both the old languages of the elves and fae , which whom the gnomes most frequently traded in the age of contact . It was strongly opposed by the humans which whom the gnomes had frequent debates about linguistics.
The relatively easy grammar of the gnomish language compared to the more complex northern languages was the main reason it eventually got adopted as the common language to communicate in. Although allot of words where borrowed from elves ("Bow" being the chief example) and others where borrowed from fae ("Magic" obviously the most well known example, even eventually substituting the word "Miracle" in some context of "Divine magic") the grammar was almost a one on one transition from the old gnomish grammar.
Out of character
The language is represented by the UK-English language while playing