You can now access the optional tomb slightly northeast of the camp, but still in the southeast section of the overall area, just south of the large rock hill. Use the rope ascender to destroy the heavy barricade. Inside you'll find some [SHOTGUN SHELLS]. Move through the cracks and use a rope arrow to cross the river.
At the camp, move left to find some [ARROWS], or head to the center of the area to find more [ARROWS]. The idea here is to turn the wheel with your axe at the start of the area (at the camp). This will cause the buoy to circle around the center, and move the pole to the left side, allowing Lara to swing to an otherwise inaccessible platform. From there, you can shoot a rope arrow into the device below to turn it halfway; the buoy will reach it anf turn it further, allowing Lara to reach another pole to swing towards the climbable wall. Your reward is [1250 XP], [250 SALVAGE], [HANDGUN PARTS] and the [TREASURE MAP] of the area. By now you can probably upgrade your handgun into a [MAGNUM PISTOL]. Bring out the zombies!
Temple of the Handmaidens Tomb puzzle solution.
: To cross the river to the other side, you'll have to time your jump at the very last moment you can actually make the leap to the rope, or otherwise Lara can't catch it.