Gun

Watch the video. Pay attention to what the Indian says when you are escaping.

This mission seems quite lengthy at first, but is actually quite short.The first thing on your agenda is saving all the required Red Indians. One is near where you begin, another is near Soapy and the final is past some stairs in a small room that can be hard to see at first glance. After you've done so, follow the Red Indians instructions, they're very clear and you can't go wrong as long as you do exactly what he says. Eventually Soapy will pick a lock, then follow him through the cave (you'll gain a bow) and keep progressing.

When you've climbed up a bit, you'll get your weapons off one of the corpses but keep with the bow for now. With some timing you'll be able to get through this section without alerting the other enemies, just watch for their routes and plan your shots accordingly. When you've finished your stealthy assault you should reach the horses, mount one and follow the road to the destination (a gate will block you at some point so slide into it to break it). For the last part of the level, you'll find the tribe under attack, crack some heads and the mission will end.