Ummmm when i looked it said the river rules apply...
Not in the first edition rules, but it is only good if they have updated the rules. Unfortunately the official rules on the DoW website is still missing this info:
There is something rotten in this Realm - not the tarnished throne
that sits atop its peak, but the struggle to get there...
Place the Rusted Throne atop the Peak, as per the map.
The Rusted Throne is a Popular Place, its Special Power granted to whoever
occupies the Peak upon which it sits. The player whose (active or in decline)
race occupies this Region receives a tribute of 1 Victory Coin for each players’
(active or in decline) piles of race tokens that occupy one of the 5 Regions
sharing a border with the Peak and its Rusted Throne. When a Lost Tribe
occupies one of these Regions, the player on the Throne collects its tribute
directly from the Victory stash.