The 3,000 main roads mentioned in novels usually referred to a fictional world or a setting in the novel to describe the various roads and cities in this world. The number 3,000 could be a concept set by the author or it could be to emphasize the complexity and variety of this fictional world. However, in reality, there was no such thing as the 3,000 Great Dao. China had the Great Wall of China and the United States had countless freeways and city streets, but these roads added up to less than 3,000. As for why the number 3,000 was set in the novel, it might be for some logical or narrative purposes, such as to shock the readers or to explore the various possibilities in the novel world. However, the number 3,000 was just a fictional concept and should not be understood as a real number in the real world.