Like は and も, the possessive particle の can also append itself to other particles to help modify nouns.
|To send a letter to a friend.|
|A friend’s letter.|
|A letter to a friend.|
Note that にの is not a valid combination. We must use the directional particle! This is a key grammatical strength of へ.
|To receive a letter from a friend.|
|A letter from a friend.|
|To have a conversation with a teacher.|
|A conversation with a teacher.|
|To commute by train.|
|A commute by train.|
|The distance from Tokyo to Kyoto is about 380 kilometres.|
In writing you may occasionally see へと used in combination but this does not change the meaning or grammatical usage. This will not come on the N5 or N4, but you may see it later.
|During the 20th century Japan moved from an industrial society to a technological one.|