It's a Showdown, I Am the Emperor of the Tang Dynasty!

Traveling to the Tang Dynasty, I was told that the system had not been activated yet. What to do? We can only prosper the country through our own industry! Li Er: "Zhang Xing, what should we do if the Turks move south?" Zhang Xing: "We are doing business and they want to join in the fun, so let's fight!" Li Er: "But there is not enough food and grass." Zhang Xing: "Don't panic at all! I just invented hybrid rice. I'll eat the food until I die!" Li Er: "No, we have no weapons." Zhang Xing: "Don't panic, look at my Italian cannon!"