Well, I own the WotC version of Talislanta so that's a bit out of date, but then again I don't think the answer to this question is really meaningfully Talislanta-ey anyway so I'll answer it.
Basically, you have to choose some variables to control, if you don't want every kind of character from everywhere going all over the place doing everything. There's a couple ways to do this.
GM-driven character creation control is either restricting race/class options, place of origin, background, or current circumstances. You may say "You all have to be serving your tour of duty in the Danuvian military." Or "you're all Drukh." Or "you all live in Mog and met while amber mining." Or "you're all reincarnators." Now, this still doesn't prevent all your Danuvian swordsmen from going AWOL and scampering off somewhere. But it does give you a starting point where you can focus in one one part of the world or culture, and ideally the players will respond to that.
I did this with my current campaign, I said "You are all going to be starting as pirates on a pirate ship out of the Shackles; take a useful skill why don't you." Then they bought a bar on land. Whaddya gonna do. (Rhetorical question, burn the bar down and chase them out of town, obviously.)
Collaborative player group concept control is involving the players, or heck just letting them, come up with a focused reason not just to be together, focusing on one place, or whatnot, but share a conceit that will keep them that way. On the one hand this can require ongoing metagaming, on the other hand it can keep them on the rails, so to speak. So instead of "I make you start as Danuvian military," the players as a group decide they want to all be Danuvian military lifers and dedicate themselves to the extermination of mud people or something. This has the down side that you have to be willing to go along with their group conceit.
We did this back in an old campaign I played in. The GM had created this new world with the hook that magic was rare and feared, and sorcerers lived in towers and sometimes preyed on the populace. As a player group we wanted a reason to stay together and have a focus, so we decided we were a travelling entertainment troupe called the Wizzards, all dressed up like Gandalf on crack to entertain the locals (and conceal the fact we all had magical powers). We furthermore decided we wanted our main goal to be to hunt down and kill naughty wizards (and take their magical loot for our own, natch).
Of course these two can be done interactively/together.
Now, those answers cover any kind of campaign focus, but you're asking about a specific locality. Other things you can do to generate focus specifically on a given place are:
Make the place cool. Most of the battle here is making a specific place engaging enough that the PCs want to stay there, whether they are 'from there' or not. "You are from the Dark Coast!" "Hey, this place is a craphole, let's take the first ship out." If you want them to stay in Cymril, you've got to make sure there's no end of engaging things to do there.
Create other connections. From people the PCs like to mystical bonds so they get Tasered if they leave the county. Why does anyone love a place in the real world and stay there? Well, sometimes they don't love it, sometimes they don't have better options, but I think most of us could move most places we wanted to, but we stay where we are for various reasons - reproduce those in game.