This is the 14359th most frequent Turkish word.
olmuşlardı
"Olmuşlardı" means "they had become" or "they had been" in English.
In this sentence, 'olmuşlardı' is used in the pluperfect tense to indicate an action that had already been completed by the point of reference in the past.
Dün eve vardıklarında çoktan akşam olmuşlardı.
Yesterday, by the time they arrived home, it had already been evening.
Here, 'olmuşlardı' refers to a past success achieved before another point in the past, emphasizing completion.
Arkadaşlarım bir süre uğraştıktan sonra başarılı olmuşlardı.
After trying for a while, my friends had succeeded.
The use of 'olmuşlardı' in this case highlights a state of being that was true prior to a moment in the narrative's past.