Complex sentence: The former town of Kushimoto was part of Nishimuro District, but the town has strong ties with the city of Shingū and Higashimuro District, both in political and economic reasons, the town became part of Higashimuro District upon this merger.
Split into simpler sentences: The former town of Kushimoto was part of Nishimuro District, but the town has strong ties with the city of Shingū and Higashimuro District, both for political and economic reasons. The town became part of Higashimuro District upon this merger.