Complex sentence: Astoria was first settled by the Dutch and Germans in the 17th century; many Irish settled in the area during the waves of Irish immigration into New York City during the 19th and early 20th centuries.
Split into simpler sentences: Astoria was first settled by the Dutch and Germans in the 17th century. Many Irish settled in the area during the waves of Irish immigration into New York City during the 19th and early 20th centuries.