How are you defining "most important"? Also, would you be interested in modern Chinese history, or are you more interested in the imperial period? And if you're just interested in the imperial period, are we looking at early imperial or late imperial?

You can't really say one dynasty is the most important. And all events are significant to the history of the region, so it's not really reasonable for us to try to reduce it to a single bite-sized post. Questions regarding Chinese history here on AskHistorians are incredibly varied because it's an incredibly complex history covering thousands of years. You'll notice /u/cordis_melum who replied to you earlier has flair limited to a very short time within the history of China just in the last half of the 20th century. That should give an indication of just how much information there is out there.

So, I strongly recommend starting with Wikipedia and going from there.

You could start with Records of the Grand Historian by Sima Qian. It chronicles early Chinese history, and it was written during the Han Dynasty (206 BC - 220 AD). It obviously doesn't cover the late Han, Sui, Tang, Song, Yuan, Ming, and Qing dynasties, but it is a great starting point for reading about the early history of China (Xia, Shang, Zhou, Qin, early Han dynasties).