トンネルを抜けると雪国であった
Now, トンネルを抜ける means "to come out of the tunnel". 雪国 is the "Snow Country" and であった is the past tense of である, the "to be" verb in its literary form (according to tangorin.com).
How does と connect both these parts? What is its meaning here?
I think this 「と」 is Conjunctive particle which is used to indicate the situation right before the situation following 「と」 happened.
So I'd interpret this sentence like:
「トンネルを抜ける」 ((The person) goes through the tunnel)
happened right before
「雪国だった」 (the person finds himself in a snowy country. (← idiomatic interpretation))
That is a passage from a famous novel "Yukiguni(雪国)" written by Yasunari Kawabata.
国境の長いトンネルを抜けると雪国であった
This sentence consists of two sentences joined together by a conjunction.
｢(汽車は)国境の長いトンネルを抜けた。｣ "The train came out of the long border tunnel."
｢すると、そこは雪国だった。｣ "Then there was a snow country."
Though, a part of the sentence is made very short because it gives us the feeling of the snow scene that appears suddenly. It is a little unnatural in everyday conversation, but that is the beauty of this sentence.
