Exegesis:

auton ‘him,’ refers to Jesus.

hapan to plēthos ‘the whole crowd,’ ‘all the people,’ cf. on 1.10.

tēs perichōrou tōn Gergesēnōn ‘of the district of the Gergesenes,’ cf. on v. 26. perichōros ‘neighbourhood,’ ‘surrounding area’ (cf. on 3.3 and 4.14) includes here the town Gergesa and is not restricted to the surrounding area.

phobō megalō suneichonto ‘they were hard pressed with great fear’ (cf. New English Bible). For sunechō cf. on 4.38.

autos de ‘but he,’ emphatic.

embas eis ploion ‘after getting into a boat,’ cf. on 5.3 and 8.22.

hupestrepsen ‘he returned,’ i.e. to Galilee.

Translation:

The surrounding country of the Gerasenes (preferably, Gergesenes), here virtually the same as “the country of the G.” in v. 26 (several Indonesian versions).

Asked him to depart from them, or, ‘asked Jesus to leave them (or, their region), or, to depart from there, or, to go away from their “here” (as the idiomatic expression is in Marathi).’ The prepositional phrase may sound rather redundant; hence, “asked him to go (away)” (New English Bible, The Four Gospels – a New Translation).

He got into the boat. Here again the pronoun is often better specified, ‘Jesus.’

And returned. In some versions the rendering suggests that Jesus returned at once—with the result that the next verse becomes incomprehensible. To avoid this one may shift to a rendering that expresses intention, e.g. ‘on the point of returning,’ ‘in order to return’ (Balinese, Russian Synodal Bible), or to a verb that is less specific, cf. “and left them” (The Four Gospels – a New Translation), or to a combination of both, cf. ‘intending to depart’ (Bahasa Indonesia RC).

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.