Abolition of slavery occurred as abolition in specific countries, abolition of the trade in slaves and abolition throughout empires. Each of these steps was usually the result of a separate law or action.
9th – 6th century BC in India: Jains have 15 types of female slaves,Indo-European Jain Research Foundation, Encyclopaedia of Jainism, (2001 Volume 1 p 5616, but the Tirthankaras (wise men) in Jain literature: advise "Do not injure, abuse, oppress, enslave, insult, torment, torture, or kill any creature or living being."
3rd century BC Ashoka abolishes slave trade and encourages people to treat slaves well but does not abolish slavery itself in the Maurya Empire, covering the majority of India, which was under his rule.
AD 9 In China, Emperor Wang Mang usurps the throne, abolishes slave trading (although not slavery), and institutes radical land reform
It should be noted that many of these changes were reversed in practice over the succeeding centuries.