A short history about Persian Empire
The declaration is widely regarded as the "first charter of human rights", among others due to the call for the abolition of slavery worldwide and for the freedom of choice of profession, the practice of freedom of religion as reported here and the mention of Babylonian slaves being freed.
Part of text of the declaration
Now that I put the crown of kingdom of Iran, Babylon, and the nations of the four directions on the head with the help of (Ahura) Mazda, I announce that I will respect the traditions, customs and religions of the nations of my empire and never let any of my governors and subordinates look down on or insult them until I am alive. From now on, till (Ahura) Mazda grants me the kingdom favor, I will impose my monarchy on no nation. Each is free to accept it , and if any one of them rejects it , I never resolve on war to reign. Until I am the king of Iran, Babylon, and the nations of the four directions, I never let anyone oppress any others, and if it occurs , I will take his or her right back and penalize the oppressor.
And until I am the monarch, I will never let anyone take possession of movable and landed properties of the others by force or without compensation. Until I am alive, I prevent unpaid, forced labor. To day, I announce that everyone is free to choose a religion. People are free to live in all regions and take up a job provided that they never violate other's rights.
No one could be penalized for his or her relatives' faults. I prevent slavery and my governors and subordinates are obliged to prohibit exchanging men and women as slaves within their own ruling domains. Such a traditions should be exterminated the world over ......