[...] At the Saint-Germain treaty in 1919, Italy received from the Entete as "price" for entering into the war against Austria-Hungary all those parts of the county of Tirol that lay on the southwestern, Italian-bound side of the watershed [...]
The definition of the border through the watershed (with the exceptions pointed out by
flocke) still has implications today: The highest point of the Brenner Base Tunnel will be exactly under the border, in order not to alter the border-defining watershed even inside the tunnel.