Complex sentence: On November 1,2004 Masuda absorbed Mino District (the towns of Mito and Hikimi) and Mino District was dissolved as a result of this merger.
Split into simpler sentences: On November 1,2004, the towns of Mito and Hikimi (both from Mino District) were merged into Masuda. Therefore, Mino District was dissolved as a result of this merger.