The "Coolie Trade", as it eventually became known as, expanded during the 1840s and 1850s and is believed to have began sometime in and around the 16th century.Some of these laborers signed contracts based on misleading promises, some were kidnapped, some were victims of clan violence whose captors sold them to coolie brokers, while others sold themselves to pay off gambling debts. From 1847 to 1862, most Chinese contract laborers ("coolies") bound for Cuba were shipped on American vessels and numbered about 600,000 per year. Conditions on board these and other ships were overcrowded, unsanitary, and brutal. The terms of the contract were often not honored, so many laborers ended up working on Cuban sugar plantations or in Peruvian guano pits. Like slaves, some were sold at auction[9] and most worked in gangs under the command of a strict overseer.

Both contemporary observers and present researchers[who?] have frequently mentioned the similarities between the Coolie trade and the African slave trade.[11]In fact the growth of the Coolie trade was believed to have been spurred due to the worldwide movement to abolish the slave trade and thus the West needed to transition to a substitute labor and or reserve labor to African slaves while the slave trade was gradually fading.

Many coolies were first deceived or kidnapped and then kept in barracoons (detention centres) or loading vessels in the ports of departure, as were African slaves. Their voyages, which are sometimes called the Pacific Passage, were as inhumane and dangerous as the notorious Middle Passage.Mortality was very high. For example, it is estimated that from 1847 to 1859, the average mortality for coolies aboard ships to Cuba was 15.2 percent, and losses among those aboard ships to Peru were 40 percent in the 1850s and 30.44 percent from 1860 to 1863.

They were sold like animals and were taken to work in plantations or mines under appalling living and working conditions. The duration of a contract was typically five to eight years, but many coolies did not live out their term of service because of the hard labour and mistreatment. Those who did live were often forced to remain in servitude beyond the contracted period. The coolies who worked on the sugar plantations in Cuba and in the guano beds of the Chincha Islands (the islands of Hell) of Peru were treated brutally. Seventy-five percent of the Chinese coolies in Cuba died before fulfilling their contracts. More than two-thirds of the Chinese coolies who arrived in Peru between 1849 and 1874 died within the contract period. Among the four thousand coolies brought to the Chinchas in 1861, not a single one survived. Because of these unbearable conditions, Chinese coolies often revolted against their Chinese and foreign oppressors at ports of departure, on ships, and in foreign lands.

The coolies were put in the same neighbourhoods as African Americans and, since most were unable to return to their homeland or have their wives come to the New World, many married African American women. Due to the coolies' especially coolies from East and Southeast Asia (although this was most likely due to the fact that often times they came to their new home countries without Asian women and or their wives) constant interracial relationshps and marriages with Africans, Indigenous peoples, and many other groups of ethnicities this formed some of the modern world's Afro-Asian and Asian Latin Americanpopulations.

However, there are significant differences between the Coolie trade and the African slave trade. First, despite the many recorded cases of deceiving and kidnapping coolies, probably not all coolies were forced into bondage, though it is difficult to know what percentage of the total was represented by voluntary coolies. Owing to famines, wars, and shortages of land, many southern Chinese chose to go overseas to seek a better life. Of the voluntary coolies the United States and South Africa were the only recorded countries where the coolie slaves were found by evidence to have been voluntary.Second, not all coolies remained in bondage for life. Some of them became free after serving out their contracts; a few even managed to return to China and other home countries. Coolies received wages, although usually they were paid much less than local workers. Although there are reports of ships for Chinese coolies carrying women and children, the great majority of the Chinese coolies were men. Finally, their home governments (the Chinese government in particular), although were not able to give the coolies as much protection as they needed, showed concern for them. Central and local governments tried continuously to regulate and curb the coolie trade; at one point, the central government even sent inspectors to America to investigate conditions and intervene on the coolies' behalf. The Chinese government also took an active part in the final elimination of the coolie trade in 1874.