Why do people in different places speak with different accents? Please help me.

The current northern dialect, that is, the northern dialect represented by Mandarin, is actually the language furthest away from ancient Chinese. Due to years of war in the north, northern ethnic minorities continued to invade, and the northern Han people who stayed in the area assimilated with the foreign ethnic groups and gave rise to the northern dialect. During the war, many Han people were forced to move south. The south is mostly mountainous, which is not easy to fight and is less affected by the disasters of war. Therefore, ancient Chinese can be preserved in the dialects of the south. At the same time, the essence of Han culture and the tradition of poetry and rituals are passed down from generation to generation. It was also preserved in the south. Because the south is crisscrossed by mountains and waterways, and the inconvenience of transportation makes people less likely to communicate with each other, the dialects in various regions gradually diverge, giving rise to more and more small dialects. Precisely because the southern region is a dialect area, it is culturally more open than the northern region. Because small languages ??cannot gain cultural communication advantages, they must learn other large languages ??to make up for their own language weaknesses. Almost all southerners speak languages ??other than their native dialect. This multilingual advantage is conducive to a broad vision and different ways of thinking. Therefore, in modern times, southern culture is actually more open and developed than northern culture. This can be proved by the fact that the starting point of the modern revolution was in the southern region. It was the open culture of the southern region that first introduced modern revolutionary ideas and concepts. Of course, what I said above was mainly to refute the point above, and it went a bit far. To answer your question specifically, the most important reason is that geographical factors determine language differences. There are many plains in the north, and people have convenient transportation and mutual communication, which makes the language converge; while the south is mountainous and watery, transportation is inconvenient, and people communicate less, so the language development shows differences.