Didn't the Emperor Qin order all historical documents from before his time to be destroyed? Maybe there's some lost history in there or something.
The first slip recorded a multiplication table, the second held the name of the ancient city, the third reflected the relationships of local ethnic groups and the fourth was engraved with historical data concerning the Qin Dynasty (BC.221-BC.207) which followed the Warring States period. ,,, looks like they knew the value of time capsules.