The sight of adventurers or new faces who didn't look like desert natives wasn't pleasant to that group of mercenaries, and they weren't willing to chat.
"We arrived here first," one said, "This is our Oasis."
Even Damian, who knew nothing about the place he was in, knew very well that no one could go and claim an Oasis like that. If it had some buildings in it, and people living, that might be the case, but that Oasis in particular. No shot.
They were just creating excuses to stay on top of the situation. A way to make themselves believe they were the right ones in this whole mess.
Those mercenaries judged Damian by his jovial appearance; for them, he was just a boy who wouldn't have the courage to stand against them. That was quite the mistake.