During the Muslim Agricultural Revolution, the Caliphate understood that real incentives were needed to increase productivity and wealth and thus enhance tax revenues. A social transformation took place as a result of changing land ownership giving individuals of any gender, ethnic or religious background the right to buy, sell, mortgage and inherit land for farming or any other purpose. Signatures were required on contracts for every major financial transaction concerning agriculture, industry, commerce and employment. Copies of the contract were usually kept by both parties involved.