Complex sentence: After Jesus' failure to re-appear in that year, the movement lost much of its fervor and entered a "quietist" phase, which lasted throughout the 17th century, but during the 18th century, the movement mostly died out in northern India.
Split into simpler sentences: After Jesus' failure to re-appear in that year, the movement lost much of its fervor and entered a "quietist" phase, which lasted throughout the 17th century. In the 18th century, the movement mostly died out in northern India.