Why was the Qin dynasty a huge turning point in Chinese history?

The Qin dynasty, which lasted from 221 to 206 BCE, marked a pivotal turning point in Chinese history as it unified China for the first time under a centralized imperial rule. It established a standardized system of weights, measures, currency, and writing, which facilitated communication and trade across the vast territory. The dynasty also initiated significant infrastructure projects, including the Great Wall and an extensive network of roads, enhancing security and connectivity. Furthermore, its authoritarian governance set a precedent for future dynasties, influencing China's political and cultural landscape for centuries.