Linked from
The 8 pages that link to Riemannian distance, each with the reason it gives.
Metric tensorBroader topic: Curve lengths computed from the metric induce distances between points.
Riemannian manifoldRelated: It gives the manifold an intrinsic distance derived from its metric.
Levi-Civita connectionRelated: Geodesics of the connection locally realize this metric distance.
Myers's theoremRelated: The diameter conclusion bounds this distance uniformly across the manifold.