Complex sentence: Historian Marcel Trudel has documented close to 2,000 Pawnee (in French, Panis) slaves who lived in Canada until the abolition of slavery at the end of the 18th century, making up close to half of the known slaves in French Canada.
Split into simpler sentences: Historian Marcel Trudel has documented that the Pawnee ("Panis" in French) held close to 2,000 slaves in Canada until the abolition of slavery at the end of the 18th century. The Indian slaves comprised close to half of the known slaves in French Canada.