Unity in Writing, Diversity in Speech: The concept of 方言 (fāngyán) is central to understanding the Chinese linguistic landscape. For millennia, a single writing system (Chinese characters) unified a vast empire of people who spoke mutually unintelligible languages. An official from Beijing and a merchant from Guangzhou couldn't understand each other's speech, but they could communicate perfectly through writing. This is the historical foundation of the 方言 concept.
Comparison to Western “Dialects”: This is the most crucial point of differentiation. In the West, a “dialect” (e.g., Texan English vs. Scottish English) almost always implies mutual intelligibility. In China, the major 方言 groups (like Mandarin, Wu, Yue/Cantonese, Min, Hakka) are as different from each other as the Romance languages are. Calling Cantonese a “dialect” of Mandarin is, from a linguistic standpoint, like calling Portuguese a “dialect” of Spanish. The term 方言 is a political and cultural label that emphasizes a shared Chinese identity, rather than a purely linguistic one.
Mandarin's Role and Dialect Preservation: The Chinese government has promoted Standard Mandarin (普通话, pǔtōnghuà) for decades to ensure national cohesion and ease of communication. While this has been incredibly successful, it has also led to the decline of many local 方言. In recent years, there has been a growing movement and sense of cultural pride in preserving and revitalizing local 方言, which are seen as carriers of unique local culture, history, and identity.