Today, people often live outside the mountains without knowing the history of their withdrawal from the plains. During the Tang and Song dynasties, as the economic and cultural center moved from the Yellow River basin to the Yangtze River basin, a large number of people moved north to the south, and the South China tigers completely withdrew from the plains. The idioms such as "adjusting the tiger to leave the mountain", "releasing the tiger to return to the mountain", "watching the tiger while sitting on the mountain" and other idioms later showed that people had mistakenly believed that the tiger was a mountain species and did not know that the tiger was "forced to go up the mountain" because of human activities. What is the most accurate summary of the main point of this text? ["Clarify people's misunderstanding about the area where tigers live.", 'Describe the history of tigers retreating to the mountains with human activities.', 'illustrates the era background of the tiger "forced to the mountain".', 'Analysis of the impact of human activities on the living environment of tigers.']