Diplomacy is the key. All we need is communication.Illy will not let us move a city through exodus within 10 squares of a yellow (neutral) city, or within 5 squares of a green (friendly) city. This can however be overruled by claiming sovreigny level 5. Sov lvl 5 takes over a week, and is costly if done from afar. It's easier and less costly to do a double exodus, but it still takes time.
This is where troops come into play. They need to occupy the square long enough to claim the sov, and is thereby visible and can be scouted. If I found such an occupying army close to my own city, then I would ask why, contact the player, and hopefully get a proper answer. If there is no answer, and I notice the sov levels climb, I would ask my alliance for help. That is why we won't accept troops on our land. Fighting NPC is one thing. Seiging a city (maybe with our permission) might be OK too, but ask first to make things easier. A tourney is usually limited to certain squares, and shouldn't be a problem either.
If someone settles a city close to my own without asking, I would send a message to that player, and ask why, what they want and so on. If the player is reasonable, there is probably no problem with it, but if they don't reply, or are hostile, then a document with our rules made public like this, would be very helpful.
Some areas are crowded. That is a fact.
The 10 square rule is almost impossible to keep in such an area, but we must always talk about it. Setting up an agreement between two players about what squares each will claim sov for, is an excellent idea. I have done so myself, except the player I did it with has gone, and the cities have been whiped. We talk in the alliance as well, when moving cities, and ask for help to find the best spot depending on what we plan to do with that city.
I know that some people try to find fault with what others say. That is why we always need to talk, to clear up any misunderstandings. It's easy to make fun of statements set forth by alliances, that is part of the game of life, not just Illy. But the words need to be said and explained.
Look upon the 5 squares as the garden surrounding a house, and the 10 squares as the rest of the plot of land. It's easy to give away land to someone who is nice and asks, but when someone suddenly starts camping in your back yard without asking, you get upset.
We protect our gardens, our plots of land, even if there is no sov claimed on it yet. We plan ahead. Please don't step on our toes, and set up camp on our door-steps. That is all we ask.