Haocheng Traveled Through Time

Haocheng accidentally fell into the sea, and when he woke up, he traveled back to ancient times. In ancient times, there was an iron box that made sounds, called a mobile phone... What did Haocheng do in ancient times? Are there any huge differences between ancient times and modern times? Will he rely on modern technology to teach ancient people to develop? Will he tamper with history? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.