I am playing a game of Civilisation 5 - Gods and Kings (no BNW), Emperor difficulty. I am playing as Mongolia and my closest neighbour is America, with Carthage on my other side.
The map is Continents and just so happens that America is landlocked with eradicating me being the only way to expand for them. As America goes wide every time, they soon start to covet my lands so strongly that it leads to war.
My position is pretty much optimal, with all necessary resources. I wanted to go wide & warmongery, but I'm facing a problem - America runaways pretty quickly and overruns me. If I expand towards them, getting a great 2nd city spot, they attack me by turn 70, if not - about a 100. Now, for some strange reason, America is able to pump out about 5 cities by that time and just flood my borders with endless troops that they produce faster than I can kill them off, even if I go totally militaristic.
What can I do? Is there a guide for that situation anywhere?