Climb/jump to the right along the narrow handholds until you can't go any farther...
...and Lara is hanging from a ledge with a snow-covered bush growing on it. Take a long leap to the right and try to latch onto the next climbable wall.
The rock crumbles, and Lara loses her grip. press Interact as she falls...
...to latch onto the wall below.
Climb to the ledge above on the right and follow it toward the tomb entrance.
You'll pass a ledge on the left. Ignore it for now. You'll return this way after exploring the tomb. Continue forward onto another narrow stone bridge.
The bridge collapses as you try to cross...
...so you must jump forward and press Interact again to latch onto the climbable wall ahead.
From there, jump over to the next section of rough wall, climb to the top, and traverse along the narrow handhold to the right.
Then continue climbing to the right until you can pull up onto the ledge in front of the tomb.