How to deal with land-grabbing in OCC?

[Ilkuul]

In OCC, how would you respond to a situation where an enemy city is built overlapping your city radius, and due to incursions of barbarians or enemy units, they are able to grab a couple of your tiles (maybe including a special!)? Place units there and risk provoking hostilities? I only have MGE, where the AI is pretty aggressive and often just doesn't listen when you try to sweeten them with gifts...

[airdrik]

The way you deal with the units of other civs is you ally with them and it doesn't matter where he puts his units, they won't take away from the squares you work, barbarians just need to be dealt with forcefuly. To deal with other cities using your squares, just move some military unit over to that square (as long as you don't have an alliance yet), then change production to that square and call for an alliance (and remove the unit).

[Smash]

occupy the square with a unit and a caravan,dip or settler.They order you home but the caravan,dip or settler remain on the square.Using this you can build a fort for a more permanent occupation

[geofelt]

prevention of the situation is best. A city on a peninsula is optimal. The ai will not build a city next to a unit. Keep some positioned so that the ai builds a city that does not overlap. Also, the ai prefers good terrain like grassland or plains for a city, reducing the number of places to guard. They might build on forest, but certainly not often.

[Ming]

While it is still early in the game, and your non settler has nothing better to do, look at all the grasslands and plains squares around your city that could be used as city locations for an AI that would cause overlap problems. Start converting them to worthless terrain to build cities on. Works like a charm
If an AI finds you early, make peace with them, and just keep a unit near any settler that approaches your city. As noted, they won't lay down a city if a unit is next to them. Then, just identify the problem sites and get your settler working on them

[Ilkuul]

Many thanks to y'all for these most helpful suggestions! I think I like yours the best, Geofelt & Ming! - tho' it's interesting to see the variety of ways people have dealt with this problem...