What get's built first?

As my second post, can anyone tell me in what order and when the computer decides to build structures and train units??

Having a large empire, I had to wait 50 odd years for a boat to get built in one territory, the same with troops there, meaing it was eventually lost to the allmohads, as I had nothing there to assist in defending.

Can anyone help?

Basically the AI builds "from North to South". Scotland and Norway gets things built first, then comes Mercia and Denmark etc etc.

Get enough income and then everything gets built in time. If you don't have that much income, carefully select what you want to be built and only queue that...