" Holland didn't have any black colonies "..

The Dutch had several possessions in Western Africa. These included the Dutch Gold Coast, the Dutch Slave Coast, Dutch Loango-Angola, Senegambia, and Arguin. They built their first two forts on the Gold Coast in 1598 at Komenda and Kormantsil (in present day Ghana). link

....The enslaved men, women, and children who arrived in New Netherland came from a variety of African backgrounds, but a large majority of them were of Central African origins. Dutch merchants had established trade relations along the West Central African coasts, and Dutch control of Luanda (in present-day Angola) from 1641 to 1648 further promoted Dutch trade with this Central African region'''''. link

The colonization of (Dutch) Surinam is marked by slavery. Plantations relied on slave labour, mostly supplied by the Dutch West India Company from its trading posts in West Africa, to produce their crops. Sugar, cotton, and indigo were the main goods exported from the colony to the Netherlands until the early 18th century, when coffee became the single most important export product of Surinam. Planters' treatment of the slaves was notoriously bad[2]—historian C.R. Boxer wrote that "man's inhumanity to man just about reached its limits in Surinam" wikipedia, Surinam, Dutch colony