Are you interested in the history of Japanese language?
In the 7th-8th century Japan had only Kanji and at that time sentences were lined as Chinese. What is the roots of Kanji?
The roots of Kanji is these pictorial symbols to represent objects or meanings. Kanji is based on shape of objects like hieroglyphs of Egypt. This is called shoukei moji in Japanese.
Also Kanji has some kind of roots in addition to above.
This is called shijimoji which means the words to instruct. Shijimoji originally expressed abstruct meanings by illustrarions.
This is called kaiimoji which puts two words together to produce another meaning.
Though Kanji is daily used in China, Japan, Singapore and Korea (Korea abolished the use of Kanji in 1970’s but still some people can read ), but pronunciation is different in each area. That’s why even if Japanese people can understand what Chinese are written about by reading Kanji we can’t speak Chinese at all and vise versa.
If you want to know more about Kanji, please try to read books on Kanji!