When was the written language invented?

There's no single answer to when "written language" was invented, as it developed independently in different parts of the world. Here's a breakdown:

* Earliest known writing: The earliest known writing system is cuneiform, which emerged in Mesopotamia around 3500 BC.

* Other early writing systems: Other writing systems developed around the same time, including:

* Hieroglyphics in Egypt (around 3200 BC)

* Indus Valley script (around 3000 BC)

* Chinese characters (around 1500 BC)

It's important to note that:

* Writing developed gradually: The earliest forms of writing were simple, often used for recording numbers or lists. They evolved over time into more complex systems capable of expressing language fully.

* "Invention" is a simplification: The development of writing wasn't a single event, but rather a long process of innovation and experimentation across different cultures.

So, while 3500 BC marks the earliest known writing, it's not the "invention" of writing in a singular, definitive sense.