Fundo Escuro                                                                      Territories

Almost every living animal has a piece of land which he defends from other animals mainly of the same species. 
It's the so called "territory instinct".
A territory is vital for an animal because  it gets its food from there. (see Pronouns )
The main reason why an animal expels others from the territory is the food, that means survival.
After many centuries of civilization we, the human beings, still keep in a dark corner of our minds the territory sense very clear.
Our home is our private territory and we can, or should I say we must, defend it against any intruder even killing if necessary. The Law is very clear about this Defense Right.
In another sense we have the need of "personalizing" our working place. We attach pictures of our family on the computer monitor, or on our desk. Some people don't even allow, or at least don't like, others to sit down at their desk.
In a restaurant people arrange glasses silvery and dishes forming a small "territory" on the table and nobody likes when somebody crosses the "frontier" to get the salt for example. People usually say: " If you want something just ask and I'll give you" - in other words they are saying: "If you need to enter my territory you must have my permission" - it's instinctive and inevitable.
Of course our education puts some brakes in our instincts and prevents us from fighting for stupid reasons. 
On the other hand its more polite, and safer , to respect other people's possessions and territories mainly at work.
Start watching people around you, not only at work but everywhere, and you'll notice the territory clearly marked on the restaurant table, on the working desk and the private room in  a company.
 It's very interesting and educational to notice that.
By the way, dogs piss on the streets because they smell other dogs and they do so to put their private mark on the territory. Watch your dog. It will certainly do it !
People usually complain a lot if you cross the "frontier" physical or imaginary, of their precious territories.
That complaint is the  "pissing in the territory" equivalent.
Now that you have some tips about territory it's easier to understand other people's behavior, isn't it?
Remember! The next time you need something from other people's "territory" just ask for it. It's more polite and safer.

Have a look at Adjectives