Complex sentence: In the early years of European settlement it was an important trading post and shipping port as the sea was the easiest way to transport goods and people to the Manawatu and the Manawatu River was then the main access to the rich hinterland.
Split into simpler sentences: In the early years of European settlement it was an important trading post and shipping port as the sea was the easiest way to transport goods and people to the Manawatu. The Manawatu River was then the main access to the rich hinterland.