Sentence wording

Is this sentence correctly worded, particularly using the two 'them' to refer to the Thayans? FYI- Valindra is one of the Thayans.
Before the Thayans moved deeper into the ancient stronghold, Valindra used a magical scepter to summon the pit fiend Beealtimatuche from the Nine Hells to protect them from the dwarf ghosts and to assist them in the imminent engagements against the primordial’s servants and Bruenor’s group.