Complex sentence: The outcasts rowed over to Narragansett territory, and bought land from Canonicus and Miantonomi, chief sachems of the Narragansetts, Williams and twelve "loving friends" then established what Williams called "Providence", because they felt that God's Providence had brought him there.
Split into simpler sentences: The outcasts rowed over to Narragansett territory, and having secured land from Canonicus and Miantonomi, chief sachems of the Narragansetts, Williams established a settlement with twelve "loving friends". He called it "Providence" because he felt that God's Providence had brought him there.