Why are there so many dialects in Zhejiang?

I am also thinking about this phenomenon. Their dialects here have different sounds and different languages. It's weird. Taking Hangzhou as an example, Xiaoshan dialect is different from Hangzhou dialect, Fuyang has its own dialect, Dengxin Town of Fuyang has its own dialect, jiande city has its own dialect, and Tonglu County also has its own dialect. Outside Hangzhou, Ningbo has its own dialect, and Cixi in Ningbo has its own dialect. Shaoxing, Taizhou, Jinhua, Lishui, Quzhou, Huzhou, Jiaxing and Wenzhou all have their own dialects. That's weird.