。
Before long, she came into my room.
Literal
[topic-は] before-long I [genitive-の] room [into-に] entered-came.
入ってきた is the compound verb 入る ('enter') + ~てくる ('come [doing]'), in the past tense — 'came in [to where I was].' Like 戻ってくる, the deictic auxiliary ~てくる orients the motion toward the speaker. The に here marks the destination (into the room), not the location. The sentence has the cadence of narrative — a particular moment in a story (perhaps a tense or quiet domestic scene, the woman entering as the speaker is doing something).