March 25 (Reuters) - Britain marked 200 years on Sunday since its first law abolishing trade in African slaves received royal assent, a major step towards ending the practice that shipped more than 10 million Africans overseas into slavery.

Here are some key facts about the slave trade:

* WHAT IS IT?

-- The condition in which one human being was owned by another. A slave was considered by law as property, or chattel, and deprived of most of the rights ordinarily held by free persons.

* TYPES OF SLAVERY:

-- Two basic types have been identified throughout recorded history: most common was household, patriarchal, or domestic slavery.

-- The other -- productive slavery -- was less common and used slave labour for economic production, such as on plantations. It occurred primarily in classical Greece and Rome, in 9th century Iraq, among the Kwakiutl Indians of the American Northwest and in a few areas of sub-Saharan Africa, and was widespread in the Americas as a result of the Atlantic slave trade.

* THE FIRST SLAVES:

-- Slavery is known to have existed as early as the Shang dynasty (18th-12th century BC) in China. It existed in Chinese society until the 20th century, in a similar way to the rest of the world: slaves were those captured in war, in raids, and the sale of insolvent debtors.

-- Slavery existed in ancient India, where it is recorded in the Sanskrit Laws of Manu of the first century BC. It was hardly documented until British colonials in the 19th century studied it with a view to abolition. In 1841 there were up to 9 million slaves in India.

-- In England in 1086 about 10 percent of the population entered in the Domesday Book were "serfs" -- sometimes regarded as slaves although they generally had more rights than most.

* SLAVERY IN AFRICA:

-- Slavery was practiced everywhere even before the rise of Islam, and black slaves exported from Africa were widely traded throughout the Islamic world. Up to 18 million Africans were delivered into the Islamic trans-Saharan and Indian Ocean slave trades between 650 and 1905.

-- In the second half of the 15th century Europeans began to trade along the west coast of Africa, and by 1867 at least 10 million -- estimates range as high as 60 million -- Africans had been shipped as slaves to the New World.

* THE END:

-- The fate of slavery in most of the rest of the world apart from eastern Europe depended on the British abolition movement, which was initiated by English Quakers in 1783 when they presented the first important antislavery petition to parliament. Britain's "Abolition of Slavery" act of March 1807 forbade trading in slaves with Africa, and in 1833 abolished slavery entirely across its empire.

-- The United States also took a step towards abolition in 1807 when Congress passed a ban on importing new slaves from 1808. But it was nearly half a century, in which the pro-slavery southern states seceded triggering the Civil War, before President Abraham Lincoln's Emancipation Proclamation came into force on Jan. 1, 1863 and the subsequent 13th Amendment to the Constitution abolished slavery in 1865.

-- Some parts of Africa and much of the Islamic world retained slavery at the end of World War One. For this reason the League of Nations, later the United Nations, took on the obligation of ending slavery.

-- The League had considerable success in Africa, with the assistance of the colonial powers, and by the late 1930s slavery was legally abolished in Liberia and Ethiopia. After World War Two the United Nations Universal Declaration of Human Rights and the European Convention of Human Rights proclaimed slavery immoral and illegal.

Sources: Reuters/Encyclopaedia Britannica

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