Upon killing Beem-Ja, a letter can be found on his body. The letter indicates that Salma's father does not trust him, but accedes to his killing Gathrik in order for him to obtain the "book [he wants] so badly," on the condition that he ensure his daughter's safety. This book turns out to be the 2920, Frostfall, a Conjuration skill book.
Once outside, go back into Ironbind Barrow. The Dragonborn can either jump on top of the pressure sensitive altar (where the enchanted helmet is/was) to open the iron gate that is now stuck closed or look for the pull chain, located nearly above it. Proceed back towards the throne room. Beem-Ja will be standing alone outside the entrance. Kill him while the both are still outside the throne room. In this scenario he will not have the opportunity to raise the slain Warlord Gathrik from the dead, so the Dragonborn can simply loot the room/corpses, learn the Shout, and leave unscathed through the exit. (Note: If the Dragonborn is able to Soul Trap Gathrik or disintegrate him with a shock spell, Beem-Ja will not be able to revive him.)
Upon the start of fight with Beem-Ja, by entering non-combat stance Beem-Ja will say "You're not worth it" and ceases to attack player. NB, Warlord Gathik (re-summoned) remains hostile, and Salma will still continue to attack Beem-Ja.
If the player waits for long enough before confronting Beem-Ja after killing Warlord Gathrik, Salma leaves the room.
Salma's father seems to have been Beem-Ja's master/owner and had struck a deal to release Beem-Ja from servitude over some secret, no-doubt sinister event that occurred in Black Marsh.
Beem-Ja can be revived and makes an excellent support character if the Dragonborn has the Dead Thrall spell.
Note that Salma is in no way affiliated with Beem-Ja's motives, and will assist you when Beem-Ja betrays you.
If you run straight in and kill Gathrik quickly, before Beem-Ja and Salma finish off the SkeletonMage and Frost Atronach, Beem-Ja will be killed by the remaining enemies whilst he is talking to you about your sacrifice. Salma, who has become an ally adopts the crouched position of a defeated companion and can be revived with a spell. This is much easier than fighting both Warlord Gathrik and Beem-Ja.