There are twelve that we know of. In historical order, from oldest to newest, they are the Shang, the Zhou, the Qin, the Han, the Sui, the Tang, the Song, the Yuan, the Ming, the Qing, the Republic, and Mao Zedong. (Look up the Chinese dynasty song for pronunciations and a catchy song that’ll be stuck in your head all day.)
The most recent would be that of Mao Zedong, or the communists. However, each of the twelve dynasties contributed something to China’s history. In fact, for most of history, China was a world power, and it’s mainly due to the way China was ruled.
Quick note: I say that there are twelve dynasties that we know of because China is a very old country. There are probably more that have been lost to time.