Complex sentence: Throughout this turbulent period, Fatsa lost a significant number of its people as they migrated away to jobs in Turkey's larger cities or abroad, including the largest proportion of the Turkish community in Japan.
Split into simpler sentences: Throughout this turbulent period, Fatsa lost a significant number of its people as they migrated away to jobs in Turkey's larger cities or abroad. Immigrants from Fatsa constitute the largest proportion of the Turkish community in Japan.