Tried a fort in the flank of a mountain, wilderness, small trees, nothing special.
I was in the first winter, in the process of building the workshops, (and panicking about a soon-to be water problem), with around 13 dwarves, when suddenly... centaurs. Thousands of thems. Well, 4, actually. They rushed straight into my fort, and slaughtered everyone. My 3 man squad of random dudes with wooden weapon got literally crushed, and they then proceeded to kill everything and everyone.
I have crossed centaurs before, and never had problem with them, as long as i didn't attacked them.
I just had 2/3 guys outside, cutting wood and gathering plants. They went unharmed, so the centaurs weren't after them. They just rushed inside the main corridor, hunting everyone one, 20 z-level deeps in the workshops, stockpiles, they even "felt" a guy accross my in-construction military complex, rushed through the tunnels, and killed a mason against the archery target he was installing.
Are they supposed to be so aggressives?
They weren't the fortress mod kind, i don't even have it activated, and didn't get an ambush message. They were just wild donkey-mens who decided to go FB mode.
How i am supposed to fight back against this, or similar threats, in early fort? I need the ressources outside, barricading with 10 dwarves isn't really an option.