This is the 50th most frequent Urdu word.
تھی
"تھی" is the feminine singular past tense form of "was" in English.
The word "تھی" is used to describe the existence of silence in the past for a feminine singular noun.
کلاس میں خاموشی تھی۔
There was silence in the class.
The word "تھی" indicates the past tense expectation related to a feminine noun (بارش).
بارش ہونے کی توقع تھی۔
Rain was expected.
The word "تھی" is used here as the past tense auxiliary verb for a feminine singular subject in a continuous tense.