## 2 Data and Methods  
### Overview of the Study Area  
Sichuan Province is located in the southwestern part of China, with a total area of 486,000 square kilometers. The topography of Sichuan is characterized by higher elevations in the west and lower elevations in the east, with a general tilt from the northwest to the southeast. The province is predominantly mountainous, and its landform can be categorized into four types: plains, tabledands, hills, and mountains. Sichuan has a complex climate due to its varied topography. The Sichuan Basin and its surrounding areas belong to the subtropical humid climate zone, while the southwestern mountainous region of Sichuan is characterized by a subtropical semi-humid climate. The northwestern high-mountain area is a plateau cold climate zone. Human activities in Sichuan can be traced back to more than 2 million years ago during the Paleolithic Age. The Chengdu Plain, situated in the western part of Sichuan Basin, China, is a piedmont alluvial plain formed by the sedimentation of rivers, such as the Minjiang and Tuojiang. The plain generally slopes from northwest to southeast, with elevations ranging between 400 and 750 m, covering a total area of 18,810 square kilometers, as illustrated in Figure 1. The Chengdu Plain served as the cultural center of Sichuan Province from the Shang Dynasty to the Warring States period and was the core region of the ancient Shu civilization. From the Stone Age to the Warring States period, it remained a stable area for site aggregation, holding significant importance for studying the spatial distribution of sites and human-environment relationships during this era. The Chengdu Plain, developed in the Quaternary sedimentary basin at the front of the Longmen Mountains, has seen its fault activities gradually stabilize since the Middle Pleistocene, providing a geological foundation for the development of civilization in the plain area [25,26]. The hydrological system of the Chengdu Plain is primarily dominated by the Minjiang and Tuojiang river systems. The Minjiang River, the main river in the northwest of the plain, is characterized by abundant water flow and a broad valley, carrying a large amount of alluvial and proluvial deposits, which provide essential material for the formation of the plain and the fertility of its soil. The Tuojiang River, a tributary of the Minjiang, flows from the southwest to the southeast through the eastern part of the plain. Together, these two rivers form a complex hydrological network in the Chengdu Plain. The development of the river systems has created multiple terraces and alluvial-proluvial fans, and in lower-lying areas, lakes, marshes, and other wetland landscapes have formed [27,28,29]. The Stone Age (The period described is known as the Stone Age in archaeology, which is the first era used to classify early human history. It encompasses the Paleolithic (Old Stone Age) and the Neolithic (New Stone Age), spanning approximately 2.5 million years ago to around 5000-4000 years ago [30].) corresponds to the early and middle stages of the Pleistocene-Holocene, characterized by a warm and humid climate. The Pleistocene was a critical period for landform formation, with unstable geological structures, often leaving the Chengdu Plain submerged. During the Atlantic period of the Holocene, the Chengdu Plain was likely crisscrossed with waterways and dotted with lakes and marshes, with frequent flooding, which was not conducive to human activities and cultural prosperity [31; 32]. The period from the Shang to the Warring States corresponds to the Subboreal period, during which, against a backdrop of global aridity, the multiple rivers within the Chengdu Plain could provide some water replenishment, preventing the climate from becoming too harsh. Although the frequency of flooding decreased, sudden floods still occurred occasionally.