Finding the right spot

While I am well Into my second game (around 1650 AD) I have discovered that in order to have a sucessful empire and economy it requires the right placement of cities. Being apart of the Persian empire means that I am surrounded by water and mountaneous terrain so I am constantly being attacked by barbarian states. I am lucky that I have a strong army and a successful econmy because if I did not I could easily already been wiped out by other empires that border mine (Egyptian, Mongolian, Chinese, and German). I have made mistakes on two accounts in the location of my cities. The first mistake was when I built a city that was located far away from all my other cities hoping to spread my empire but that did not go well. The city was new and did not have much defense so it was not long till barbarians came to destroy it. If I had placed the city closer to another one, I probably would not have encountered the problem. I got to greedy with wanting more land. Expansion can be too fast when you cannot supply resources to newly aquired areas fast enough. I will continue on this game and be careful on placing my cities.