Zheng Yan has written many essays and academic papers. He says the most difficult part of writing books like Aged 6,000 is to convey the meaning of the research to the general public, who may have little knowledge in this regard.

"I seldom pack my writing with terms, theories and metrics. Instead, I write about what touches me the most in relics," he says.

"This is something similar to what I tell my students: Confused about writing papers? Go to your mother and tell her what you're writing about. Make her understand. If you get stuck when you're writing, then go back to the reason why you started."

Zheng Yan says he believes the relics, once excavated, break the linearity of time.

"They seem to be able to fold time and space, to connect us with our ancestors and our cultural heritage".