This is the 2814th most frequent Russian word.
сибири
"Сибири" is the genitive or prepositional case of "Сибирь," meaning "of Siberia" or "in Siberia," referring to the vast region in Russia.
Here, the word 'Сибирь' translates to 'Siberia' and is used as the subject of the sentence, representing the geographical region.
Сибирь является обширной территорией в России.
Siberia is a vast territory in Russia.
In this sentence, 'Сибири' is the genitive case form of 'Сибирь', used to denote possession specifying the peoples belonging to Siberia.
Я люблю изучать культуру народов Сибири.
I love studying the culture of the peoples of Siberia.
Here, 'Сибирь' is in the accusative case, indicating the destination of the action, specifically traveling to Siberia.