The Mongols were technically advanced, they were just not very urban. They had one of the most impressive pre-industrial mail systems in the modern world, and they are largely responsible for the sudden spread of gunpowder weapons. The problem was that not being urban also came with not being politically stable, and their culture was so ephemeral that they just sort of got absorbed by the people they conquered. 

But regarding FTL, the circumstances that would make it easy also have significant implications. Consider the amount of energy, and the mastery of the physical world, that would be required here. We're talking about a society that can harvest solar power straight from the source, and who's idea of a super-weapon would be one that destroys entire solar systems in a single flash. They would live in a world where human labor is viewed the same way we view stone tools, and who can manipulate their own genes and bodies to achieve near immortality. The culture and stability of such a society would both be difficult to understand from our perspective. And the thing is, what I am describing is probably just a near-galactic civilization. I don't know if I can fathom what possibilities lie beyond that. 

Which isn't to say that it is impossible. Just remember that, with multi-galactic civilizations, you are dealing with demi-gods.