Table S1 Geographical origin of the samples included in this study.

Table S2 Summary of microsatellite markers used in this study.

Table S3 Pairwise estimates of FST based on 25 microsatellite markers.

Table S4 Eigenvalues (λ), variance (var) and spatial autocorrelation (I) for all spatial principal components.

Table S5 Mantel correlation coefficients and p-values for models in which the cost for travelling along three different branches of the Silk Roads vary independently from one another.

Fig. S1 Least-cost paths between populations with trade route : nontrade route cost ratios of 1:1 (model [T0]) with origins in (A) ALT, (B) BFG, (C) CHA, (D) CHY, (E) GGA, (F) IND, (G) KAL, (H) KAR, (I) KKA, (J) KSW, (K) KYR, (L) LTA, (M) NUR, (N) UKL, (O) UKZ, (P) YAR.

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