The cause for the scattering, the persecution, was stated previously. This can be stated in active form. AT: "who had fled the great persecution and had gone" (See: [[rc://en/ta/man/translate/figs-activepassive]])
The phrase "went down" is used here because Samaria is lower in elevation than Jerusalem.
# the city of Samaria
Possible meanings are 1) Luke expected the readers to know which city he was writing about. AT: "the main city in Samaria" or 2) Luke did not expect his readers to know which city he was writing about. AT: "a city in Samaria"