Complex sentence: Sarah then explains to Kyle that the Guardian was sent to protect her from the T-1000 back in 1973, where the Terminators'arrival caused a fractured timeline that differs from Kyle's.
Split into simpler sentences: Sarah then explains to Kyle that the Guardian was sent to protect her from the T-1000 back in 1973. The arrival of the Terminators'arrival caused a fractured timeline that differs from Kyle's.