Learn Hardcore Finnish: Viime kesänä en matkustanut ulkomaille, vaan jäin kotimaahan. - Last summer, I did not travel abroad; instead, I stayed in my home country.

Viime kesänä translates to "last summer." It serves as a time adverbial, and in Finnish it’s common to place such expressions at the beginning of a sentence to set the temporal context for what follows.

Why is the negative marker en used before matkustanut?

In Finnish, negative sentences use a special negative auxiliary instead of a separate word like "not." Here, en is the first person singular negative auxiliary. It is combined with the past participle (matkustanut) of the main verb to indicate that the action (traveling) did not occur.

Why is the verb matkustanut in its past participle form rather than a simple past tense form?

Finnish forms negative compound tenses by pairing the negative auxiliary (in this case, en) with the past participle of the main verb. Matkustanut is the past participle of matkustaa ("to travel"), and using it with en expresses that the action of traveling abroad did not take place.

What grammatical case are ulkomaille and kotimaahan in, and why is that case used?

Both ulkomaille and kotimaahan are in the illative case, which indicates movement towards a destination. In the sentence, ulkomaille means "abroad" (i.e., traveling to foreign lands), while kotimaahan means "to the home country." This case is used with verbs that express motion or a change of location.