This is the 2747th most frequent German word.
kannten
"Kannten" is the past tense form of "kennen," meaning "knew" (to be familiar with someone or something).
Here, 'kannten' is the preterite (simple past) form of 'kennen' used to indicate knowledge or acquaintanceship in the past.
Wir kannten die Antwort nicht.
We did not know the answer.
In this case, 'kannten' is used to express familiarity with the city in past events.
Sie sagten, dass sie die Stadt gut kannten.
They said that they knew the city well.
Here, 'kannten' describes the state of recognizing or being acquainted with someone in a past situation.