Complex sentence: In 1828, the first German immigrants settled in Paraná, but large numbers of immigrants from Germany did not arrive in Curitiba until the 1870s, most of them coming from Santa Catarina or the River Volga from Russia.
Split into simpler sentences: In 1828, the first German immigrants settled in Paraná. However, large numbers of immigrants from Germany only arrived in Curitiba during the 1870s, most of them coming from Santa Catarina or Volga Germans from Russia.