Double penetration, starting from being a trader

Ordinary citizen Chen Feng accidentally obtained a painting that could lead him to another world.
Through the power of the scroll, he began to resell items back and forth between the two worlds.
Ordinary ores obtained in the other world and transported to the modern world immediately became strategic materials for the military.
However, the insignificant small items in the modern world will be bought at a high price in an instant in another world...
Originally, Chen Feng just wanted to be a trader and live a peaceful life.
But as he explored the other world in depth, he discovered that this world not only had warriors, but also immortals.
This time Chen Feng was completely upset...
PS: This book is also known as "Not handing over your abilities is because you are afraid of death" and "On whether Jindan monks can withstand nuclear bombs".