Slavery existed in the area of later Saudi Arabia from antiquity onward.
Hejaz (the western region of modern day Saudi Arabia), which encompasses approximately 12% of the total land area of Saudi Arabia, was under the control of the Ottoman Empire from 1517 to 1918, and as such nominally obeyed the Ottoman laws. When the area became an independent nation first as the Kingdom of Hejaz and then as Saudi Arabia, it became internationally known as a slave trade center during the interwar period. After World War II, growing international pressure eventually resulted in the formal abolition of the practice. Slavery was formally abolished in 1962.
Background
The region of the Arabian Peninsula which was renamed Saudi Arabia in 1932 was nominally under the Ottoman Empire between 1517 and 1918, and as such it nominally adhered to the same laws as the rest of the Ottoman Empire in regard to the slavery and slave trade. In 1908, the Ottoman Empire nominally abolished slavery, but this law was not enforced in the Arabian Peninsula by the Ottoman authorities.
Slave trade
Enslaved Africans were sold in the towns of the Arab World from antquity onwards.
After World War I, the area formed an independent nation as the Kingdom of Hejaz (1916–1925). Hejaz did not consider itself obliged to obey the laws and treaties signed by the Ottoman Empire in regard to slavery and slave trade. During the Interwar period, the Kingdom of Hejaz was internationally known as a regional slave trade center. The Red Sea Slave Trade was, together with the Trans-Saharan Slave Trade and Indian Ocean slave trade, one of the arenas comprising what has been called to the "Islamic slave trade", "Oriental slave trade", or "Arab slave trade" of enslaved people from sub-Saharan Africa to the Muslim world.
Richard Francis Burton described the slave market in Medina in the 1850s:The bazar at Al-Madinah is poor and as almost all the slaves are brought from Meccah by the Jallabs or drivers after exporting the best to Egypt the town receives only the refuse.... some of these slaves come from Abyssinia: the greater part are driven from the Galla country and exported at the harbours of the Somali coast, Berberah, Tajoura and Zayla. As many as 2000 slaves from the former place, and 4000 from the later, are annually shipped off to Mocha, Jeddah, Suez and Maskat. [...] It is a large street roofed with matting and full of coffee-houses. The merchandise sat in rows parallel with the walls. The prettiest girls occupied the highest benches. Below were the plainer sort and lowest of all the boys. They were all gaily dressed in pink and other light-colored muslins with transparent veiles over their heads; and whether from the effect of such unusual splendor or from the re-action succeeding to their terrible land-journey and sea-voyage, they appeared perfectly happy.
By the 20th-century, slaves were primarily trafficked from West Africa, East Africa, the Arabian Peninsula, the Levant, and South-Western Asia.
A former Royal Air Force pilot, who trafficked slaves from Africa into Arabia in the 1950s stated: “That’s where all roads end … Arabia”, since Saudi Arabia was the center and end station of modern chattle slavery at the time, and drove the expanding slave trade market after WII.
In the UN debate against slavery in 1957, Saudi Arabia was at the center of the debate since it was the hub of the slave trade network of the Arabian Peninsula, which kindnapped and enslaved people from Africa, the Aden Protectorate, the Trucial States, Baluchistan, and further away.
First slave route
The slave trade had two major routes to Hejaz. African slaves were trafficked from primarily Sudan and Ethiopia. Primarily children and young women were bought or given as tribute by their parents to Ethiopian chiefs, who sold them to slave traders. The parents were told that their children were going to be given a better life as slaves in Arabia. The slaves were delivered to Arabian slave traders by the coast and shipped across the Red Sea to Jeddah.
Eunuchs, female concubines and male labourers were the occupations of slaves sent from Ethiopia to Jidda and other parts of Hejaz. The southwest and southern parts of Ethiopia supplied most of the girls being exported by Ethiopian slave traders to India and Arabia. Female and male slaves from Ethiopia made up the main supply of slaves to India and the Middle East.
Egypt and Hejaz were also the recipients of Indian women trafficked via Aden and Goa. Since Britain banned the slave trade in its colonies, 19th century British ruled Aden was no longer a recipient of slaves and the slaves sent from Ethiopia to Arabia were shipped to Hejaz instead.