What are the influences of events, places and previous literature works on the Middle-Earth world? How “far” went Tolkien to create it?

The aim of this map is to show the places that had an influence on Tolkien's creation of Middle Earth.

Source: Garth, John. 2021. I Mondi di J.R.R Tolkien: I luoghi che hanno ispirato la Terra di Mezzo. Oscar Mondadori. (Available also in the English version: The Worlds of J. R. R. Tolkien: The Places that Inspired Middle-earth, 2020)