The common writing media before paper: writing on slips and silk flourished in the Warring States and gave the hundred schools a way to spread their texts.

Shang dynasty to Eastern Jin
1250 BCE · OriginShang oracle-bone script already has the graphs for ce and dian, depicting bound slips, showing that bamboo books were in use.433 BCE · EvolutionThe slips from the tomb of Marquis Yi of Zeng are the earliest bamboo slips yet found, and writing on slips and silk flourished in the Warring States.404 · ImpactHuan Xuan of the Eastern Jin ordered paper to replace slips, and paper fully supplanted bamboo and wood for official writing.
Sources (2)
  1. 曾侯乙墓竹简展 (新华网)
  2. 档案学研究 2009 (纸代简牍)

Before paper became common, slips, boards and silk were the usual materials of writing in China, and they gave the hundred schools of thought a way to spread their texts.

The oracle-bone script of Yinxu already has characters such as ce and dian whose shapes look like bamboo slips strung together, which shows that the Shang already wrote on bundles of slips.

The tomb of Marquis Yi of Zeng in the Warring States yielded the earliest bamboo slips found so far, and writing on slips and silk then flourished in the Warring States.

Huan Xuan of the Eastern Jin ordered paper to replace slips, and from then paper wholly took the place of slips and boards as the material for official documents.

Slips & Scrolls is the class in the chapter on Crafts on the writing materials used before paper became common. Bamboo slips were already used for writing in the Shang, writing on slips and silk flourished in the Warring States, and only when Huan Xuan of the Eastern Jin ordered paper to replace slips did paper wholly take their place as the material for official documents.