Who keeps the flies away.

[AshleighWood]

I like the poem overall but was not quite sure what time period it is supposed to refer to.

The first part ("migrants", "shift", "efficiency") make it sound like it refers to a relatively modern period, whereas some of the later imagery ("natives", "furs", "castles", "siege") makes it sound more medieval. However the "red brick" houses seem to put it firmly in modern times.