From: Temporal and spatial distribution of ancient sites in Shaanxi Province using geographic information systems (GIS)
Slope/°
0–3
3–10
10–25
25–50
From Han to North and South Dynasties
42.7%
26.7%
28.1%
2.5%
Sui and Tang Dynasties
63.6%
23.3%
11.8%
1.3%