have concern for exit and entrance mean

[shinem]

As a group, they sat on ceremony: there were no introductions, no pack drill. It was like joining a group that had been sitting since the beginning of time. They had no concern for exits and entrances.

In this sentence what does speaker mean by saying "they have concern for exit and entrance mean" about the group? What does it mean?

Thanks.

[English Freak]

It means the people who set foot in the room or those who left didn't matter to them. Or they didn't care about the people who set foot in the room or those who left at all.
By the way, this the first time I have answered a question by a Turkish person. So I'd like to seize the opportunity to say I really enjoyed your country (Istanbul) when I visited it this year in March. Good for you.

[Rover_KE]

It took me a minute to realise what sounded odd about the first sentence: As a group, they sat on ceremony.

The set phrase is 'they didn't stand on ceremony'.

In this case sat does not mean didn't stand.

I agree with EF's answer (though I've never been to Turkey).

Rover

[shinem]

Thank you very much for your explanations :) They will help me indeed.

Besides I'm so glad that you've enjoyed in our country, I'm agree with you and hope that you both come to visit İstanbul again :)

[English Freak]

Thank you very much for your explanations :) They will help me indeed.

Besides I'm so glad that you've enjoyed in our country, I'm agree with you and hope that you both come to visit İstanbul again :)

If you don't mind, I want to correct a very common mistake made by most of people. We should say "I agree with ..." not "I'm agree with...".
It's actually my plan to visit your country soon once more if everything goes well.

[shinem]

Oh ok :D Thank you for correcting me... I hope you have a nice holiday again.