Complex sentence: This mourning ritual does not remain in practice today as before, some immigrants of these cultures to the United States as recently as the 1970s have loosened this strict standard of dress to only two years of black garments.
Split into simpler sentences: This mourning ritual does not remain in practice today as before. Many immigrants of these cultures to the United States as recently as the 1970s have loosened this strict standard of dress to only two years of black garments.