## 4 Discussion
### Geographic Context Controlling the Spatial-Temporal Distribution
#### 4.1.2 Distance Away from the River  
Statistical data analysis clearly showed a continuous increase in the distance to riverine water sources in site distributions since the Paleolithic era. Most archaeological sites from the Paleolithic and Neolithic periods were located between 500 and 1000 m from water. However, by the Shang and Zhou dynasties, settlements typically ranged from 1000 to 3000 m away, reflecting a notable shift in settlement patterns (Figure 4b). The concentration of Paleolithic sites within 3000 m of water highlighted the critical dependence of ancient humans on nearby water for survival. This reliance underscored their limited production capabilities and vulnerability to natural disasters, like flooding and waterlogging, making access to water essential for drinking, fishing, and other subsistence activities.  
During the Neolithic period, while the overall proximity to water remained relatively stable, there was a notable increase in the number of sites located within 500 m of water. This change suggested that Neolithic communities developed strategies to mitigate flood risks, aided by advancements in tools and the emergence of social tribes [19; 25; 27]. With more secure and diverse livelihoods, such as agriculture and animal husbandry, Neolithic humans enjoyed greater flexibility in choosing settlement locations. They balanced the need for water accessibility with protection from natural hazards, leading to more strategic site selection. Notably, seven sites were identified over 5000 m from water in the water-surrounded area of Nanpinggang Town, Changde City, during this period. These clustered settlements, though distanced from direct water access, were located on elevated terrain that protected against flooding [31]. This adaptive response to environmental challenges allowed communities to prioritize safety while still accessing essential resources.  
By the Shang and Zhou dynasties, most archaeological sites were found 1000 to 3000 m from river water. In contrast to the Neolithic period, the overall distance of archaeological sites from water increased, with a significant rise in the number of sites situated over 5000 m away (Figure 4b). This shift suggested that, during this time, humans had developed greater self-sufficiency, reducing their reliance on proximity to water. Innovations, such as irrigation systems, facilitated more intensive agricultural development, resulting in a transition from a survival-based lifestyle to one that was more sustainable and productive. As a result, humans' capability to manage environmental risks improved significantly.  
Overall, the trend in archaeological site locations from the Paleolithic onward demonstrated that most sites were situated within a range of 500 to 3000 m from water. This pattern indicated that this distance range was optimal for human development, balancing resource accessibility with the need to mitigate environmental risks [19; 25]. These insights hold valuable implications for modern settlement planning, emphasizing the importance of considering both resource access and environmental safety in community establishment.