The earliest Chinese writing appeared during the Shang Dynasty (1766 B.C – 1050 B.C.) and the earliest form is called the oracle bone script. Ancient Chinese heated the rod and inserted it into a pit in the turtle shells or animals bones and then waited until the bone cracked. Then the cracks could be read.
Legend goes that the earliest writing was invented by Cangjie who was a bureaucrat under the Yellow Emperor, the legendary ancestor of the Chinese nation. It was said that he studied the world of animals and then invented the first Chinese characters.
In the system of the early Chinese writing, it was common for the words with the same or similar sounds shared the same sign. That means one sign may be used to represent multiple words. Also, it was popular for two words which had different sounds but had related meanings to share the same sign.
As time passed by, additional symbols were used to polyvalent signs for the purpose of avoiding wrong interpretation of the writing.