The past perfect tense of the verb ‘leave’ is ‘had left’.
To explain further, the past perfect tense is used to indicate that an action was completed before another action took place in the past. In this case, ‘had left’ suggests that the action of leaving was finished before some other past event occurred.
For example, you might say: ‘She had left the party before I arrived.’ This signifies that her action of leaving happened before my arrival, establishing a clear sequence of events in the past.