This is the 8015th most frequent Turkish word.
köylülerin
"Of the villagers" or "the villagers'".
In this sentence, 'köylülerin' (of the villagers) is in genitive form, showing possession.
Köylülerin tarla işleri her gün sabah erken başlar.
The villagers' field work begins early every morning.
Here 'köylülerin' (of the villagers) defines the group associated with the action of gathering.
Köylülerin toplandığı meydan bugün çok kalabalıktı.
The square where the villagers gathered was very crowded today.
In this context, 'köylülerin' (of the villagers) emphasizes the active role the villagers have in contributing.