Here's a breakdown of the key points:
* Proto-Germanic: The ancestor of German emerged around the 5th century AD. It was spoken by Germanic tribes across Europe.
* Old High German: This stage of the language, from roughly 750 to 1050 AD, was characterized by regional dialects. There was no single "standard" German.
* Middle High German: Between 1050 and 1350 AD, the language began to evolve with greater uniformity. Important literary works emerged during this period.
* Early New High German: This period, lasting until around 1600 AD, saw the rise of a more standardized form of German. This was partly driven by the standardization of the written language.
* Modern Standard German: The 18th and 19th centuries saw the further development of a standard language that is generally recognized as "German" today. The work of the brothers Grimm played a significant role in this process.
Therefore, it's more accurate to say that German evolved gradually over centuries. While there were key milestones along the way, it's not possible to put a specific date on when it "became" a language.