Quoted By:
The treaty of Blackthorn, during the war between the clans of Johto and Kanto, Johto managed to take over the western region of Kanto, up to around Pewter City, the Johto clan managed to suffocate Kanto's supply lines, that forced the Kanto clan to accept the Johto Clans terms of the treaty which means that they also agreed authority for the Johto Clan to annex this region, thus why mount silver in particular is part of the Johto reigon
