The girl who could not read or write was taught to write her name by Ashar and his family so they could claim benefits.
Ashar's wife, Tallat, was jailed for five years on trafficking and benefits fraud charges.
The couple had pleaded not guilty.
Prosecutor Peter Cadwallader praised the victim's courage and "extraordinary resilience" in testifying in court.
When she was rescued in a police raid in 2009, the victim did not know formal sign language.
British prosecutors and police arranged specialist support so that she could participate in the court proceedings, having an intermediary and a sign-language expert to help her communicate in court.
Speaking through an interpreter and using sign language, the victim described how she was hit with a rolling pin while forced to work for no money, made to sleep on a concrete floor in a bolted cellar and sexually abused.