This is an often debated question that interests both Chinese and non-Chinese people. Some say, it is 3,000 years old, others say it is twice as much. The answer really depends on the understanding of the word “writing.” Without a clear understanding what writing is, there is no point in arguing over time periods.
Some people understand writing as any kind of abstract symbol written on a surface. Such an abstract symbol is obviously different from a drawing which has a recognizable resemblance to a physical object. Such symbols have been found on Neolithic pottery from various sites across China. There have been many attempts to link these symbols with the Chinese script, without any convincing results. The major problem is that even though there might be some symbols that can be associated with later writing, there is always a disturbingly large gap of two thousand years between the symbols.
According to a more widely accepted interpretation, writing is a graphical system that records spoken language. This means that writing depicts not abstract concepts but the sounds of a language. Writing presupposes a language, with all of its rules and functions. In other words, writing is never a set of mystical symbols that point at reality directly by means of bypassing language. The earliest examples of such writing come from the oracle-bone inscriptions of the Shang dynasty, from around the 12th century BC. However, by this time the Shang script was a fully developed writing system with over 6,000 characters, capable of recording all nuances of contemporary language. This Shang script is a direct-line ancestor of modern Chinese writing.