why no iron access over roads?

Hi,
Eight years on, I thought I would have understood how to hook up resources for my cities - but apparently I don't.

Olmec at 9 o'clock and Tiwanaku at 2 o'clock do not have access to the iron at 5 o'clock. Why is that? They are connected by roads, and Tiwanaku also by culture. I guess the basic access to the iron goes via the coast in the bay West of the Iron peninsula to the roaded tile 1S of Cuzco. From there on it should spread to all cities, like it spreads to Machu Picchu and Rome. Why not? Both cities have access to Machu Picchu's goldmines-

the short answer : there is a blockade
the long answer : there is a barbarian galley thats sea blockading traderoutes out of S.E city (building Moai).
My guess is, next turn those cities that are building swordsmen, will empty their queue, coz they dont have iron too.

Hmmm.. barbs galley blockade water tiles to connect East South city with others cities (road here 1S of Cuzco won't help - you need visible coast line from city to city or fortress inside your borders that act like city for connection, not "just road tile next to coast", still you need riverside fortress or connect it by road).
And Cuzco won't be able to finish Swordsman even if you see it 1 turn from finish - it will show "can't continue.... " message next turn.. If you would go in city screen, you would not be able to build new iron unit anywhere else outside South East city...