does it mean that only one club can claim a 'territory' then?
Yes. And if another club rides through it without prior approval and doesn't take off their colors (vests/jackets) they'll be assaulted or worse. If say a club goes to a party or visit say a gravesite or rides through rival territory for some rally like bike week in Daytona they will have to first contact a president who will grant them sage passage provided that they remove their vests.
mean, if one guy from each club meets in some rural petrol station when they're both filling up their bikes
If it's an angel and a Mongols, angel and an outlaw they're going to fight right away 99% of the time. Generally 1%ers don't go after non1% clubs and others aka civilians, unless they're disrespected or someone starts with them first. But rival clubs are fair game at any time.
There's a lot of rules. Can't touch a members bike or God forbid sit on it. Women can't join. Many clubs don't accept people who aren't white. Women are shared unless they're identified as property of a member. When riding in a group no one gets split up meaning everyone goes the same speed and will run red lights to keep everyone together. Many require workouts and if not you pay a fine. Weekly meetings. There's a ton...
Fairly recently two rival clubs the bandidos, another large worldwide club like the ha and outlaws, and the cossacks, which is fairly large but aren't international, ran into each other at a restaurant. 10 people were killed and something like 200 arrested. They had to use city buses to take the dudes to jail for processing lol.