Complex sentence: Originally the Ibo District was divided into three towns (Ibogawa, Shingou, Mitsu) which in October of 2005 along with the town of Tatsuno merged into a single city with the name of Tatsuno.
Split into simpler sentences: Originally the Ibo District was divided into three towns (Ibogawa, Shingou, Mitsu). In October of 2005 the three towns along with the town of Tatsuno merged into a single city bearing the name of Tatsuno.