What is the earliest known writing in China? In what period? What is its historical position?

The earliest systematic characters were found in Oracle Bone Inscriptions of Shang Dynasty.

Oracle Bone Inscriptions is one of the Chinese characters, and it is also the oldest mature character in China. Oracle Bone Inscriptions is also called Wen Qi, tortoise shell or tortoise shell animal bone. After divination with tortoise shell and animal bones, Shang people used knives to engrave the divination time, the names of the diviners and the things they divined, and some even engraved the good and bad luck that came true a few days later. However, the specific situation varies with the stage of Oracle bones. Generally speaking, the inscriptions in Wuding period are the most complete and the most abundant in existence. Scholars call this kind of record Oracle Bone Inscriptions, and this kind of writing is Oracle Bone Inscriptions. A large number of Oracle bones with Oracle Bone Inscriptions were unearthed in Yin Ruins, all of which have the basic structure of Chinese characters. A large number of Oracle Bone Inscriptions and inscriptions not only recorded the political, economic, military, meteorological and divination situation at that time, but also marked the maturity of the writing. The picture shows Oracle Bone Inscriptions carved on the tortoise shell.