What were some key technology that the tang dynasty had?

Tony, engraving typography and gun powder were invented. A monk called Seng Yixing created Da Yan Calendar, which accurately reflected how son moves. He was also the first one who measured the length of meridian line.

Tang Ben Cao was the first and earliest pharmacopeia issued by the government. And Tang people made great progress in architecture. Zhaozhou Bridge was the first stone arch bridge.