나는 인도 여행을 떠났다.

English Translation

I was on a trip to India.

Here are some other examples of using “떠나다” in a similar way as “여행을 떠났다”:

집을 떠났다. (Left home)
회사를 떠나기로 했다. (Decided to leave the company)
그녀는 외국으로 떠날 예정이다. (She is planning to leave for abroad)

In these examples, “떠나다” is used to express the action of leaving or departing from a particular place or situation.