[Photo provided to China Daily]

Longshan Eggshell Black Pottery Cup

Collection: Shandong Provincial Institute of Cultural Relics and Archaeology

Period: Neolithic era

Some 4,000 years ago, on the banks of the Yellow River, the Longshan Culture brought the most rustic material and the most sophisticated craftsmanship together. Very few of these thin-sided black pottery cups have ever been unearthed.

Eggshell black pottery cups in various shapes have been found, suggesting that they were not part of a single batch.

The sophisticated manufacturing techniques were unique for their time. Even with the use of modern technology, it's hard to reproduce the extreme thinness of the original.

Pottery this thin will easily shatter on a fast-spinning wheel. Such small vessels place high demands on the wheel's precision and stability.

No kiln site associated with the time and place of these vessels' manufacture has been found, so we do not know what equipment was used 4,000 years ago.

Eggshell pottery was made from the fine silt deposited in rivers and lakes. Washing it and removing the impurities rendered this basic material strong enough to be made into thin but durable pottery.

The temperature in the kiln and the length of firing determined each vessel's fate.

The ancient potters used a unique sealed firing technique that allowed carbon to infiltrate the pores of the pottery. This produced a completely black surface, which was then glazed.