Complex sentence: Furthermore, Hobson only claimed to have taken possession of the North Island by Treaty; the South Island he claimed by right of discovery, observing that Māori were so sparse there that it could be considered uninhabited.
Split into simpler sentences: Furthermore, Hobson only claimed to have taken possession of the North Island by Treaty. The South Island he claimed for Britain by right of discovery, by observing that Māori were so sparse in the South Island, that it could be considered uninhabited.