Complex sentence: Schomburg immigrated to New York on April 17,1891 and settled down in the Harlem section of Manhattan; here he continued amassing the information needed to untangle the African thread of history in the fabric of the Americas.
Split into simpler sentences: Schomburg immigrated to New York on April 17,1891 and settled in the Harlem section of Manhattan. He continued his studies to untangle the African thread of history in the fabric of the Americas.