Partial trade network disappeared

[buck beach]

I am playing a game under build 5409 (I think). Between the years 1334AD & 1335AD , my offshore trading partners were dropped from my trading network (excepting one I think, there still may be one.) Hope you can give me some explanation I just overlooked. Ran another turn past 1335AD and the network somehow reestablished back to normal, Strange?

 

[Walter Hawkwood]

Your only viable maritime route is through Carthage, and it got blocked by pirates. You can even see that:



The northern route that you see to France is blocked by barbarian cities and wasn't usable for quite a while as an alternative route.