Complex sentence: Tarrant Abbey Farm was in medieval times the site of Tarrant Abbey, founded in the 12th century by Ralph de Kahaines (of nearby Tarrant Keyneston) as a Cistercian nunnery, later supposedly the richest in England.
Split into simpler sentences: Tarrant Abbey Farm was in medieval times the site of Tarrant Abbey. It was a Cistercian convent founded in the 12th century by Ralph de Kahaines (of nearby Tarrant Keyneston), and becamae of one of the richest Cistercian nunneries in England.