Complex sentence: The bishop received no aid whatever, so that he was obliged to depend upon the contributions from the few white settlers in the territory, many of whom refused to pay the tithes which he had found it necessary to impose.
Split into simpler sentences: The bishop received no aid and he was obliged to depend upon the contributions from the few white settlers in the territory. Many of them refused to pay the tithes which he had found it necessary to impose.