Fig 1.
Location of nodes on Silk Routes used in quantifying Centrality (red) along with NGA locations (black).
Fig 2.
Spread of horse-mounted Cavalry.
Data from [63].
Fig 3.
Data from [67].
Fig 4.
MilTech trajectories in Seshat NGAs, divided by major world region: (A) Europe and Africa; (B) Western Asia; (C) East and SE Asia; (D) Americas and Oceania.
Fig 5.
“Technological leaders”: NGAs that at some point achieved the highest MilTech score available at that time.
Fig 6.
Results of similarity analysis.
NGAs are binned into 6 categories according to the earliest time they share 10 or more MilTech variables with another NGA, displayed by color: dark red = 2500 BCE or before; orange = between 2500 and 1500 BCE; yellow = between 1500 and 500 BCE; green = between 500 BCE and 500 CE; blue = after 500 CE; grey = did not display any similarities during our sample period. Unfilled red circles indicate Silk Route Nodes as in Fig 3.
Table 1.
Regression results for the best (lowest AIC) regression model.
Table 2.
Alternative model selection results.